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Development and validation of a novel non-invasive index for predicting fibrosis in patients with chronic hepatitis B
infection: a retrospective cohort study.
Journal: BMJ Open
Manuscript ID: bmjopen-2015-008032
Article Type: Research
Date Submitted by the Author: 25-Feb-2015
Complete List of Authors: Feng, Limin; The First Affiliated Hospital, College of Medicine, Zhejiang University, Laboratory Medicine Sun, Ke; The First Affiliated Hospital, College of Medicine, Zhejiang
University, Pathology Zhang, Jie; The First Affiliated Hospital, College of Medicine, Zhejiang University, Laboratory Medicine Feng, Guofang; Women’s Hospital, School of Medicine, Zhejiang University, Reproductive Endocrinology Zhao, Ying; The First Affiliated Hospital, College of Medicine, Zhejiang University, Laboratory Medicine
<b>Primary Subject Heading</b>:
Diagnostics
Secondary Subject Heading: Gastroenterology and hepatology, Infectious diseases
Keywords: HISTOPATHOLOGY, Hepatology < INTERNAL MEDICINE, INFECTIOUS DISEASES
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Development and validation of a novel non-invasive index for predicting fibrosis
in patients with chronic hepatitis B infection: a retrospective cohort study.
Limin Feng1, Ke Sun
2, Jie Zhang
1, Guofang Feng
3, Ying Zhao
1*
1Department of Laboratory Medicine, The First Affiliated Hospital, College of
Medicine, Zhejiang University, Hangzhou 310003, China
2Department of Pathology, The First Affiliated Hospital, College of Medicine,
Zhejiang University, Hangzhou 310003, China
3Department of Reproductive Endocrinology, Women’s Hospital, School of Medicine,
Zhejiang University, Hangzhou 310006, China
*Corresponding author:Ying Zhao
Department of Laboratory Medicine, The First Affiliated Hospital, College of
Medicine, Zhejiang University, Qingchun Road 79#, Hangzhou 310003, China
E-mail: [email protected]
Tel.: +86-571-87236380
Fax: +86-571-87236383
Short title: a novel non-invasive index and liver fibrosis
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Abstract
Objective: A liver biopsy is the “reference standard” for diagnosing and staging liver
fibrosis but with many disadvantages. Therefore, developing non-invasive index for
predicting fibrosis is very valuable. We developed and validated a novel non-invasive
index for predicting significant fibrosis in patients with chronic hepatitis B infection.
Design: A retrospective cohort study.
Setting: Chronic Hepatitis B virus infected patients were recruited in the Department
of Infectious Disease in the First Affiliated Hospital of Zhejiang University.
Participants: A total of 506 patients were enrolled, and patients were randomly
divided into estimation (n=253) and validation (n=253) cohorts.
Primary and secondary outcome measures: Chronic Hepatitis B virus infected
patients were studied retrospectively using routine parameters. A novel index was
developed from an estimation cohort and validated in another cohort. Liver histology
was assessed for fibrosis according to Xi’an Meeting Scoring System. The novel
index was compared with ten other indices using receiving operating characteristics
curves. Multivariate forward stepwise regression analysis revealed that alpha fetal
protein and activated partial thromboplastin time were significantly associated with
the Xi’an Meeting Scoring System, and were used to calculate the novel index.
Results: The novel index predicted significant fibrosis with an area under the curve of
0.822, exhibited a significantly higher area compared to the other ten indices in
estimation cohort, and was validated in the validation cohort.
Conclusions: The novel index can be used to predict significant fibrosis, and may
decrease the need of liver biopsy in patients with chronic hepatitis B infection.
Keywords: Chronic Hepatitis B virus; non-invasive index; liver biopsy; Xi’an
Meeting Scoring System
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Strengths and limitations of this study
▪The AA index had an AUROC curve of 0.822, 0.845, and 0.893 respectively for All
patients, patients with ALT< 2×ULN, and patients with HBeAg negative for
predicting significant fibrosis.
▪The AA index exhibited a significantly higher AUROC for the prediction of
significant fibrosis compared with some non-invasive Indices.
▪According to the cutoff values of 0.007 and 0.127, the presence of significant fibrosis
was predicted with high sensitivity (90.0%) and high specificity (88.4%).
▪Hepatic fibrosis was evaluated only using the Xi’an stages.
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Introduction
Chronic hepatitis B virus infection (CHB) poses serious public health problems, and
can progress to liver fibrosis, liver cirrhosis, and hepatocellular carcinoma 1
. The
degree of liver fibrosis is an important parameter in the determination of appropriate
antiviral treatment and prognosis for patients with CHB 2,3
.
The "reference standard" for evaluating the degree of liver fibrosis is liver biopsy 3.
However, liver biopsy has some recognized limitations, such as its invasive nature,
pain, sampling error, inter-observer variability, non-dynamic evaluation of liver
fibrosis, and even a small risk of life-threatening complications 2,3
. Due to these
limitations and risks, it is desirable to investigate novel non-invasive methods to
evaluate liver fibrosis 4. These methods include biological approaches based on serum
biomarkers of fibrosis and physical approaches based on the measurement of liver
stiffness using transient elastography 3. In recent years, some non-invasive indices
based on routine serum biomarkers have been demonstrated to have high diagnostic
accuracy and cost-effectiveness in identifying significant fibrosis and cirrhosis in
patients with CHB and/or hepatitis C 5,6
.
The aim of this study was to develop a novel predictive index based on routine
parameters for predicting significant fibrosis according the Xi’an Meeting Scoring
System 7 in patients with CHB. The diagnostic performance of the new index was
then compared with that of several indirect non-invasive indices, including AST to
ALT ratio (AAR) 8, AST to platelet ratio index (APRI)
9, Forns index
10, platelet count
(PLT), age, AST, and INR index (FIB-4) 11
, fibro-quotient (Fibro Q)12
, AST, platelet,
GGT, and AFP index (APGA) 13
, Platelet, Age, Phosphatase, AFP, and AST index
(PAPAS) 14
, Göteborg University Cirrhosis Index (GUCI) 15
, RDW to platelet ratio
(RPR) 16
, and Globulin-platelet model (GP) 17
.
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Subjects and Methods
Subjects
Seven hundred eighty-seven consecutive patients with CHB, including 476 male and
311 female aged 18–84 years (40.0±11.4 years) seen by the Department of Infectious
Disease, The First Affiliated Hospital, College of Medicine, Zhejiang University
(China) between July 2010 and December 2013 were considered for inclusion in the
study if they had received liver biopsy and a fasting serum sample collected on their
first admission. A diagnosis of CHB infection required a previous history of hepatitis
B or hepatitis B surface antigen (HBsAg) positivity for >6 months, and persistently
positive HBsAg and/or hepatitis B virus (HBV) DNA 18
. Exclusion criteria included
age under 18 years, concurrent infection with hepatitis C virus, hepatitis D virus,
hepatitis G virus, and/or human immunodeficiency virus, any autoimmune liver
disease, hepatocellular carcinoma, metabolic liver disease, alcoholic liver disease (20
grams per day for females, 30 grams per day for males), liver transplantation, and
decompensated cirrhosis. Two hundred eighty one patients were excluded because the
above reasons. Finally, 506 patients (337 male and 169 female, 37.45±9.60years)
were enrolled retrospectively. Written consent was obtained prior to liver biopsy, and
the trial was approved by the Ethics Committee of the First Affiliated Hospital,
College of Medicine, Zhejiang University, China. After receiving a liver biopsy (as
described below), the cohort was randomly divided into estimation (n=253) and
validation (n=253) cohorts for derivation of the prediction model for significant
fibrosis and subsequent validation.
Data Collection
Patient demographics and laboratory parameters were recorded on the first admission.
These included age, gender, HBsAg and HBeAg status, HBV DNA levels, alanine
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aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL),
triglyceride (TG), total cholesterol (Tch), total protein (TP), albumin (ALB), alkaline
phosphatase (ALP), gamma glutamyl transpeptidase (GGT), fasting plasma glucose
(FPG), alpha fetal protein (AFP), activated partial thromboplastin time (APTT),
D-dimers, fibrinogen, prothrombin time (PT), the international normalized ratio (INR),
hemoglobin (Hgb), red cell distribution width (RDW), White blood cell (WBC), Red
blood cell (RBC), and platelet count (PLT). The upper limit of normal (ULN) of ALT
was 40 U/L in men and 35 U/L in women. The real-time fluorescent polymerase chain
reaction system (7300; Applied Biosystems, Inc., Carlsbad, CA, USA) was used to
detect HBV DNA levels, with a lower limit of detection of 20 IU/ml. The ALT, AST,
TBIL, TG, Tch, TP, ALB, ALP, GGT, and FPG levels were measured on a Hitachi
7600 automatic biochemical analyzer (Hitachi Ltd., Tokyo, Japan) using Roche
Diagnostics GmbH reagents (Roche Diagnostics, Mannheim, Germany). HBsAg,
HBeAg, and AFP levels were measured on an Architect Ci8200 automated
immunoassay analyzer (Abbott Laboratories, Abbott Park, IL, USA) using Abbott
reagents. APTT, PT/INR, and Fbg were measured by a coagulation method using a
Sysmex CA7000 system (Sysmex, Kobe, Japan) and Siemens reagents (Siemens,
Marburg, Germany) 19
. INR was calculated from the PT according to the formula:
INR = (PT/mean normal PT) International Sensitivity Index (ISI)
20
. WBC, RBC, and PLT count
was assessed using a Sysmex XE-2100 automated hematology analyzer (Sysmex
Corp, Kobe, Japan) using Sysmex reagents.
Liver biopsy
Liver biopsy enables the reliable diagnosis of hepatic lesions, and is an important aid
to treatment and prognosis. For patients with HBV, liver biopsy is used for grading,
staging, exclusion of comorbidities, evaluation of the degree of fibrosis and/or
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inflammation and is an important factor in the choice of an antiviral treatment strategy
21. The indications for liver biopsy in the current study were: viral hepatitis,
autoimmune hepatitis, cholestatic liver diseases, storage diseases and metabolic
diseases, acute liver failure, liver transplantation, tumor, and hepatopathy of unknown
cause 21
. All patients underwent percutaneous liver biopsy guided by ultrasonography.
Liver biopsy was performed using 18G BioPince biopsy needles (InterV-MDTech,
Gainesville, Florida). A minimum of 1.5 cm of liver tissue with at least 5 portal tracts
was required for appropriate diagnosis. The specimens were fixed, paraffin-embedded,
and stained with hematoxylin and eosin (HE). The histologic staging of liver fibrosis
(S0 to S4) of liver biopsy specimens were analyzed according to the Xi’an Meeting
Scoring System 7 by a single pathologist who was unaware of patient characteristics.
Hepatic fibrosis was assessed using the Xi’an Meeting Scoring System as follows: S0,
no fibrosis; S1, fibrosis confined to portal tracts, periportal spaces, and perisinusoidal
spaces, or fibrous scar in the hepatic lobule; hepatic lobular structure integrity; S2,
bridging fibrosis, mainly caused by bridging necrosis; most of hepatic lobular
structure integrity; S3, a lot of fibrous septa are separated and/or involve the hepatic
lobule with distortion of the lobular structure, but without obvious cirrhosis; possible
with portal hypertension and esophageal varices; S4, early cirrhosis, liver parenchyma
is damaged extensively, with diffuse fiber hyperplasia, liver cells are in various
degrees of regeneration, and false flocculus is formed 7. S0 and S1 were considered to
indicate no fibrosis, while S2, S3, and S4 were considered to indicate significant liver
fibrosis.
Published Non-invasive Indices for Predicting Significant Liver Fibrosis
Some published non-invasive indices for significant fibrosis were calculated for each
patient based on previously described formulas, which have been summarized in
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Table 1. The indices included AAR 8, APRI
9, Forns index
10, FIB-4
11, FibroQ
12,
APGA index 13
, PAPAS index 14
, GUCI 15
, RPR 16
, and GP 17
.
Statistical Analysis
Statistical analysis was performed using SPSS16.0 (SPSS Inc., IL, USA) and
MedCalc v.9.3 software (MedCalc, Mariakerke, Belgium). Data are presented as
mean ± SD or median (range), and categorical data are presented as percentages. For
continuous variables, the differences between two groups were assessed with an
independent samples t-test or the Mann-Whitney U test, as appropriate. Categorical
variables were analyzed using the chi-square test. Spearman's rank correlation test
was used for correlation analysis. Multivariate forward stepwise regression analysis
was used to assess the association between the clinical/ laboratory parameters and the
Xi’an Meeting Scoring System fibrosis stages and to develop an index for predicting
significant fibrosis. A predictive index was constructed by modeling the values of
independent variables and their coefficient of regression. The receiver operating
characteristic (ROC) curve was used to assess the diagnostic performance of the novel
index. Differences between the diagnostic performance of the novel index and other
non-invasive indices were compared by using ROC curves, and the area under the
ROC curves (AUROC). Statistical significance was defined at two sides as P<0.05.
Results
Baseline Characteristics of the Patients
The enrolled CHB patients were divided into two cohorts: the estimation cohort and
the validation cohort. The demographic, laboratory and histological characteristics of
the estimation cohort, validation cohort, and entire cohort are shown in Table 2. There
were no significant differences in demographic and laboratory parameters between the
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estimation and validation cohorts, except that the ALT levels were significantly
higher in estimation cohort than those in the validation cohort.
Development of a Novel Index for Predicting Significant Fibrosis
The relevant variables of the estimation cohort based on the Xi’an Meeting Scoring
System (S0-1 and S2-4) are shown in Table 3. The RDW, GGT, ALP, INR, PT, APTT,
and AFP levels were significantly higher in S2-4 group than those in the S0-1 group,
while the PLT, TP, ALB, TG, and Tch levels were significantly lower. Other
demographic and laboratory parameters were not significantly different between the
S2-4 and the S0-1 groups. Among these variables, AFP (P=0.039) and APTT
(P<0.001) were identified as independent predictors for significant fibrosis based on
multivariate forward stepwise logistic regression analysis. The relationship between
the Xi’an Meeting Scoring System stages and AFP and APTT separately are
displayed in Figure 1. It was clear from Figure 1 that as the fibrosis progressed, the
AFP and APTT levels increased. The Spearman correlation coefficient for AFP and
APTT, and the Xi’an Meeting Scoring System stages (Xi’an stages) were 0.305
(P=0.001) and 0.289 (P<0.001), respectively. A novel index (denoted the AA index)
for predicting significant fibrosis was constructed and expressed by a formula
consisting of AFP and APTT:
Log index = - 9.164 + 0.114 × AFP + 0.236 × APTT.
The chi-square Hosmer Lemershore test was 4.215 (P=0.837), and the Spearman
correlation coefficient for the new index and Xi’an stages was 0.416 (P<0.001).
Diagnostic Performance of the AA Index
The diagnostic performance of the AA index for predicting significant fibrosis was
assessed using the ROC curve. It was found that the AA index had an AUROC curve
of 0.822 (standard error (SE) =0.055; 95% CI, 0.714–0.930; P<0.001) for predicting
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significant fibrosis in the estimation cohort.
The AA index was compared with ten other published non-invasive indices, as shown
in Table 1. The AA, FIB-4, APRI, Forns, Fibro Q, APGA, GUCI, RPR, and GP
indices were all correlated with significant fibrosis (r=0.465, 0.247, 0.229, 0.253,
0.182, 0.367, 0.261, 0.272, and 0.253, respectively [all P<0.05]) in the estimation
cohort, except AAR (r=0.039, P=0.566) and PAPAS (r=0.183, P=0.063). The
AUROC of the AA and other indices for predicting significant fibrosis in all patients,
patients with ALT levels lower than the 2-fold ULN (ALT< 2×ULN), and patients
with hepatitis B e antigen (HBeAg) negativity in the estimation cohort are shown in
Table 4. The ROC curves for AA and these ten indices for all patients, patients with
ALT< 2×ULN, and HBeAg negative patients are shown in Figures 2a, 2b and 2c,
respectively. The AA index exhibited a significantly higher AUROC for the
prediction of significant fibrosis compared to AAR (P=0.003) and PAPAS (P=0.033).
No significant differences were observed between the AUROCs of FIB-4 (P=0.141),
Forns (P=0.123), APGA (P=0.444), GP (P=0.101), APRI (P=0.177), Fibro Q
(P=0.078), GUCI (P=0.262), and RPR (P=0.262) indices and AA index in the
prediction of significant fibrosis.
Definition Cut-off Values
We selected low (0.007) and high (0.127) cutoff values that achieved an excess of
90% for both sensitivity and specificity in the diagnosis of significant fibrosis in the
estimation cohort. The sensitivity, specificity, positive predictive value (PPV),
negative predictive value (NPV), positive likelihood ratio (+LR), and negative
likelihood ratio (-LR) of AA were 91.3%, 50.0%, 29.0%, 96.3%, 1.83%, and 0.17%,
respectively using a low cutoff value of 0.007, 65.2%, 90.0%, 58.8%, 92.1%, 6.52%,
and 0.39% using a low cutoff value of 0.127, respectively.
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Validation Cohort
Applying the new AA index to the validation cohort, the AUROC for predicting
significant fibrosis was 0.773 (SE=0.053; 95% CI, 0.669–0.877; P<0.001). The
AUROC in the total cohort was 0.795 (SE=0.038; 95% CI, 0.720–0.871; P<0.001).
There were no significant differences in the AUCs between the estimation and
validation cohorts (Z=0.642, P=0.521). The AA, FIB-4, APRI, Forns, Fibro Q, APGA,
PAPAS, GUCI, RPR, and GP indices all correlated well with significant fibrosis
(r=0.358, 0.247, 0.271, 0.285, 0.168, 0.323, 0.211, 0.291, 0.274, and 0.256,
respectively [all P<0.05]) in validation cohort, except AAR (r=-0.023, P=0.736). The
AUROCs of AAR, FIB-4, APRI, Forns, Fibro Q, APGA, PAPAS, GUCI, RPR, and
GP indices were 0.412, 0.670, 0.707, 0.708, 0.592, 0.745, 0.672, 0.722, 0.689, and
0.716, respectively. The AA index exhibited a significantly higher AUC in the
prediction of significant fibrosis compared to AAR (P<0.001) and Fibro Q (P=0.008).
No significant difference was observed between the AUROCs of FIB-4 (P=0.079),
Forns (P=0.154), APGA (P=0.366), GP (P=0.209), APRI (P=0.181), PAPAS
(P=0.113), GUCI (P=0.249), and RPR (P=0.132) indices and the AA index in the
prediction of significant fibrosis. The AUROCs of AA, AAR, FIB-4, APRI, Forns,
Fibro Q, APGA, PAPAS, GUCI, RPR, and GP indices were 0.792, 0.187, 0.448,
0.556, 0.606, 0.390, 0.683,0.564, 0.633, 0.579, and 0.595, respectively, for HBeAg
negative patients, and were 0.762, 0.407, 0.665, 0.696, 0.677, 0.618, 0.698, 0.570,
0.692, 0.693, and 0.698, respectively, for patients with ALT< 2×ULN. According to
the cutoff values of 0.007 and 0.127, the presence of significant fibrosis was predicted
with high sensitivity (90.0%) and high specificity (88.4%) in the validation cohort.
Discussion
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Many studies have indicated that non-invasive indices containing simple serum
markers are valuable in the evaluation of liver fibrosis in patients with chronic liver
diseases 8-17
. Most of the non-invasive methods were developed in patients with
chronic hepatitis C (CHC) virus infections 9-12,15
. In recent years, these indices have
been used to evaluate CHB patients 13,14,16,17
. In CHB, evaluation of liver fibrosis is
crucial since HBV cannot be eradicated completely from the patient by treatment for
the persistence of covalently closed circular DNA in the nucleus of infected
hepatocytes 22,23
. European Association for the Study of the Liver (EASL) guidelines
have stated that non-invasive evaluation of fibrosis would be of interest in CHB 24
.
Although these methods cannot replace liver biopsy in chronic liver diseases, they
narrow the group who really need biopsy and provide an evaluation of liver damage
without biopsy 24
. Many clinicians have already used these tests for patients with
CHB in the same way as for CHC 21
.
The AA index was based on two routine serum parameters: AFP and APTT. The
Spearman correlation found AFP and APTT were significantly correlated with the
Xi’an stages. The addition of other variables in our study did not further improve the
accuracy of the index. AFP has been shown in previous studies to be associated with
significant fibrosis in CHB 13,14,17,25,26
. AFP is related to hepatic impairment and
chronic fibrosis and can aid in the differential diagnosis of hepatic diseases 25
. APTT
measures the intrinsic pathway of coagulation, and the APTT values are in accordance
with the fact that the degree of impairment of clotting factors is related to the severity
of liver damage 27
. There were some non-routine parameters used in some indices for
predicting fibrosis, including hyaluronic acid, a-2 macroglobulin, haptoglobin,
apolipoprotein A1, and Golgi protein 73, however, use of these parameters in
predictive models might hinder widespread use of these indices 22,25,28,29
.
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Liver biopsy also has its limitations. The AUROC in evaluating non-invasive indices
of fibrosis never reached a perfect value of 1.0, and barely reached 0.90 30,31
. Indices
such as FIB-4, GUCI, APRI, FibroQ, and Forns were developed based on patients
with CHC 9-12,15
, while APGA, PAPAS, RPR, and GP indices were developed based
on patients with CHB 13,14,16,17
. Even with using the same indices, a different study
population will lead to different results; only the APGA, RPR, and GP indices were
based on a Chinese population. The AUROC of FIB-4, GUCI, APRI, Fibro Q, and
Forns indices for CHB patients in our estimation cohort (0.691, 0.729, 0.707, 0.661,
0.687, respectively) and in our validation cohort (0.448, 0.633, 0.556, 0.390, 0.606,
respectively) were all lower than those of previous studies (0.765, 0.720, 0.880, 0.783,
0.860, respectively) with CHC patients. The one exception was that the AUROC of
GUCI in our estimation cohort was similar to that of previous studies 9-12,15
. A study
by Erdogan et al. 32
also evaluated the AUROC of FIB-4, GUCI, APRI, FibroQ, and
Forns indices in CHB patients and found that the AUROC (0.701, 0.670, 0.670, 0.588,
0.680, respectively) was lower than those in CHC patients 9-12,15
, which is similar to
the current results. The AUROC of APGA, PAPAS, RPR, and GP indices in CHB
patients in our estimation cohort (0.758, 0.630, 0.723, 0.671, respectively) and in our
validation cohort (0.683, 0.564, 0.579, 0.595, respectively) were all lower than those
of previous studies (0.850, 0.776, 0.825, 0.762, respectively) in CHB patients 13,14,16,17
.
The pathogenesis of liver fibrosis in CHB is different from that of CHC 33-36
. First, the
total amount of liver fibrosis reflected by the fibrosis area is significantly lower in
CHB than in CHC 34
. Second, hepatitis B patients tend to progress to cirrhosis with
larger nodules (macronodular cirrhosis) than hepatitis C patients 34
. Third, bridging
necrosis is the main pathogenic predictors of fibrosis progression in CHB. However,
CHC has a more progressive natural history with persistent inflammation associated
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with liver fibrosis and cirrhosis 33
. Fourth, hepatic stellate cells (HSCs) have a key role
in the development of fibrosis in chronic liver disease, and activated HSCs synthesize
and secrete chemokines, extracellular matrix proteins, and other factors, which all
contribute to remodel liver fibrosis 35,36
. HBV Dane particles and X and C protein may
induce HSC proliferation through the platelet-derived growth factor-B/PDGF
receptor-β signal pathway 36
. However, HCV core protein may directly activate
hepatic fibrogenesis a by a toll-like receptor 2-dependent manner 35
. Fifth, the liver
biopsies in these studies were assessed for fibrosis stages according to different
staging systems 9-12,14-16
, except that APGA was based on liver stiffness
measurements13
. The Scheuer 10
, Ishak 9,14,15
, and METAVIR 11,12,16
staging systems
are often used in clinical pathology, but the Xi’an stages 7
are widely used in China.
These staging systems all have advantages and disadvantages 37
. A comparison of the
four staging systems for chronic hepatitis fibrosis stages are listed in Table 5; the
selection of staging system depends on the comfort of the pathologist and the needs of
the involved clinicians 37,38
. Compared with FIB-4, GUCI, APRI, FibroQ, and Forns,
which were developed based on patients with CHC by ROC analyses 9-12,15
, the AA
index is more suitable for patients with CHB, FIB-4, GUCI, APRI, FibroQ; Forns is
more suitable for patients with CHC. The APGA, PAPAS, RPR, and GP indices were
developed based on patients with CHB 13,14,16,17
. However, the APGA was based on
liver stiffness measurements, and not on liver biopsy, and the study population of the
PAPAS index was not Chinese.
Defects in the design of diagnostic studies include problems with the study population
and bias. Despite the fact that ROC analysis is widely used in diagnostic test
evaluations, a proper design with a broad study population and avoidance of bias are
required to obtain valid and reliable conclusions in the assessment of diagnostic test
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evaluations 39
. A broad study population is required to evaluate the accuracy and
specificity. Bias can manifest in many different ways, including different diagnosis
procedures and a non-blind design. Bias can lead to a false low or high
sensitivity/specificity and, therefore, a false low or high AUC 39
. In the current study,
we included varying degrees of fibrosis (S0-S4). Although the
prevalence of severe fibrosis (S4) was low, hepatic fibrosis was assessed using the
Xi’an staging system, which led to a limitation in the comparison of AUCs. Low
(0.007, absence of fibrosis) and high (0.127, presence of fibrosis) cutoff values that
achieved high sensitivity and specificity for the diagnosis of significant fibrosis were
selected. For patients with an AA index < 0.007, significant fibrosis could be ruled out
and, for patients with an AA index > 0.127, significant fibrosis could be ruled in. A
clinician may choose not to perform a liver biopsy with AA index < 0.007 or > 0.127,
avoiding biopsy associated risks and costs, and may choose clinical follow-up instead.
International guidelines of Chronic Hepatitis B suggest that CHB patients with ALT >
2×ULN should be treated. However, recent reports have suggested that CHB patients
with persistently normal ALT levels may experience severe histologic liver damage
29,40. HBeAg negative CHB patients are usually asymptomatic for the first 30-40 years
41. The characteristics, therapy and prognosis of HBeAg negative CHB are different
from positive ones, spontaneous recovery of HBeAg negative CHB is rare, and the
long-term prognosis is poor with rapid evolution to cirrhosis and Hepatocellular
Carcinoma 41,42
. Therefore, the degree of hepatic fibrosis can guide treatment
decisions and monitor progress in patients with ALT < 2×ULN and that are HBeAg
negative 43,44
Only a few studies have addressed ALT < 2×ULN and HBeAg negative
CHB patients with hepatic fibrosis 43,44
. Our study found that the AUCs of the AA
index in our study were higher than other indices, and may be useful to predict
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significant fibrosis in CHB patients with ALT < 2×ULN who are HBeAg negative.
The present study has several limitations. First, hepatic fibrosis was evaluated only
using the Xi’an stages. Second, some liver tissue had only 5 portal tracts in the
liver biopsy. As this is less than the recommended 11 portal tracts 45
, this is a clear
limitation of the current study. Third, the AA index was developed for patients with
CHB, and the prevalence of severe fibrosis in the Chinese CHB population was low;
thus, the AA index may not be applicable to patients with CHC or other causes of
hepatic fibrosis and other ethnic populations. Fourth, some non-routine parameters
used in some indices for predicting fibrosis, including hyaluronic acid, a-2
macroglobulin, haptoglobin, apolipoprotein A1, and Golgi protein 73, were not
available for use in the current study 22,25,28,29
. Fibrotest (Fibrosure in the USA) is a
non-invasive index for predicting significant fibrosis in patients with CHC or CHB.
The laboratory parameters for calculating Fibrotest include α2-macroglobulin,
apolipoprotein A1, haptoglobin, γ-GT, and total bilirubin obtained on the same day as
liver biopsy. However, α2-macroglobulin and haptoglobin were not routinely
available in our hospital. Therefore, it was not possible to perform Fibrotest, and
compare the AUROC of the AA index for predicting significant fibrosis with that of
Fibrotest. The AUROC of the Fibrotest index for predicting significant fibrosis was
reported by Leroy et al. 22
to be 0.77 (95%CI:0.71-0.83), which was smaller than that
of our study. In contrast, Kim et al. 46
found the AUROC was 0.903 (0.838–0.968),
which was larger than that of our study. Morever, FibroScan can calculate liver
elasticity using a low frequency elastic wave transmitted through the liver, and has
been considered the most accurate non-invasive model to assess liver fibrosis among
patients with chronic liver diseases due to various etiologies 47
. While Fibroscan
certainly has value as a non-invasive measure of liver fibrosis, the instrument was not
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available in our institution. Therefore, we were unable to compare results. Therefore,
we were unable to compare our index with these indices. Fifth, although the AA index
can be accurately used to predict significant fibrosis, it cannot truly replace
histological fibrosis staging. The AA index is likely to be most useful as a supplement
to liver biopsy. Sixth, larger sample sizes as well as multi-center and multi-ethnic
studies will be necessary to validate the clinical application of the AA index. These
non-invasive indices were used to diagnose significant fibrosis (F2) and/or cirrhosis
(F4) using various AUROC and cutoff values. However, if only a small number of
patients with advanced fibrosis were included in the studies, the accuracy of the
non-invasive indices for higher stages of fibrosis (F3 and F4) can influence the
validity of the serum markers investigated 5,15,16
. A small number of patients with
advanced fibrosis is a limitation of the current study. In conclusion, we found that an
index (AA) containing AFP and APTT can accurately predict significant fibrosis in
CHB patients with ALT< 2×ULN that are HBeAg negative. The AA index is more
accurate than the AAR, APRI, Forns, FIB-4, FibroQ, APGA, PAPAS, GUCI, RPR,
and GP indices. The parameters used in the AA index are widely available, and can be
used as non-invasive index to predict significant HBV-related fibrosis. Use of the AA
index may decrease the need of liver biopsy in patients with CHB.
Contributors YZ and LF contributed to the study conception/design. LF, KS, JZ, and
GF contributed to the data collection. YZ and LF conducted the data analysis,
critically revised the article and reviewed the draft of the article.
Funding This work was supported by grants from the Department of Education
Foundation of Zhejiang Province, China (Nos. Y201017380 and Y201330146). The
funders had no role in study design, data collection and analysis, decision to publish,
or preparation of the manuscript.
Competing interests None.
Patient consent Obtained.
Ethics approval This study was approved by the ethics committee of the First
Affiliated Hospital of Zhejiang University School of Medicine, China.
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Figure Legends
Figure 1. Box-plots displaying the values of alpha fetal protein and activated partial
thromboplastin time based on Xi’an Meeting Scoring System.
The top and bottom of each box represents the 25th and 75th percentile interval. The
line through the box in the median and the error bars are the 5th and 95th percentile
intervals. AFP, alpha fetal protein; APTT, activated partial thromboplastin time.
Figure 2. Receiver operating characteristic curves for prediction of significant fibrosis
in the estimation cohort using the new index in comparison with several other
calculated indices.
a: all patients, b: patients with ALT< 2×ULN, c: patients HBeAg negative. AA, the
new index consisted of alpha fetal protein and activated partial thromboplastin time;
ROC, receiver operating characteristic; ALT, alanine aminotransferase; ULN, upper
limit of normal; HBeAg, hepatitis B e antigen.
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Table 1. Summary of Non-invasive Indices for Predicting Significant Liver Fibrosis
Index Formula
AAR [8] AST/ALT
FIB-4 [11] (Age×AST)/ (PLT (109/L)×ALT
1/2]
Forns index[10] 7.811–3.131×LN(PLT)+0.781×LN(GGT)+3.467×LN(age)-0.014×Tch
APRI [9] [(AST/ULN)/PLT (109/L)] ×100
Fibro Q [12] (10×age×AST×PT INR)/(PLT×ALT)
APGA [13] Log(index)=1.44+0.1490×log(GGT)+0.3308×log(AST)-0.5846×log(PL
T)+0.1148×log (AFP+1)
PAPAS [14] Log(index+1)=0.0255+0.0031×age+0.1483×log(ALP)-0.004×log(AST)
+0.0908×log(AFP+1)-0.028×log (PLT)
GUCI [15] [(AST/ULN) ×prothrombin-INR] ×100/ PLT
RPR [16] RDW/PLT
GP [17] GLOB×100/PLT
ALT, alanine aminotransferase; AST, aspartate aminotransferase; PLT, platelet count; GGT,
gamma glutamyl transpeptidase; Tch, total cholesterol; INR, the international normalized ratio;
AFP, alpha fetal protein; ALP, alkaline phosphatase; ULN, upper limit of normal; RDW, red cell
distribution width; GLOB, globulin. Units of AST, ALT, GGT, and ALP: U/L; Units of age, Tch,
AFP, GLOB, PLT, and RDW: years, mmol/L, ng/mL, g/dL, 109/L, and %, respectively.
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Table 2. Baseline Characteristics of the Patients in the Estimation and Validation
Cohorts
Variable All patients
(n=506)
Estimation cohort
(n=253)
Validation cohort
(n=253)
P value
Age (years) 37.45±9.6 37.51±10.0 37.39±9.1 0.886
Male, n (%) 337 (66.6) 166 (65.6) 171 (68.0) 0.637#
BMI (kg/m2) 22.5±3.51 22.5±3.60 22.5±3.49 0.957
WBC (109/L) 5.51±1.60 5.47±1.61 5.55±1.49 0.558
RBC (1012
/L) 4.81±0.51 4.80±0.52 4.81±0.50 0.817
Hgb (g/L) 148±18 147±19 148±17 0.501
RDW (%) 13.0±1.0 13.1±1.2 13.0±0.8 0.092
PLT (109/L) 178±53 181±55 175±51 0.191
TP (g/L) 72.2±6.7 72.5±6.7 71.8±6.7 0.268
ALB (g/L) 45.4±5.2 45.2±5.2 45.6±5.1 0.482
TBIL (µmol/L) 13 (3-436) 13 (4-436) 14 (3-280) 0.748*
AST (U/L) 30 (14-479) 31 (14-479) 30 (14-358) 0.478*
ALT (U/L) 40 (8-631) 45 (8-569) 38 (10-631) 0.019*
GGT (U/L) 25 (6-586) 25 (7-586) 25 (6-456) 0.653*
ALP (U/L) 68 (22-292) 68 (29-184) 69 (22-292) 0.871*
FPG (mmol/L) 4.72±1.41 4.64±0.90 4.80±1.80 0.268
TG (mmol/L) 0.97 (0.38-9.41) 0.99 (0.39-9.41) 0.94 (0.38-7.67) 0.780*
Tch (mmol/L) 4.47±1.04 4.46±1.03 4.47±1.05 0.917
INR 1.03±0.13 1.03±0.17 1.03±0.08 0.666
PT (s) 11.8±1.6 11.8±2.1 11.8±0.9 0.752
APTT (s) 28.2±4.8 28.2±5.4 28.2±4.2 0.952
Fbg (g/L) 2.31±0.61 2.31±0.64 2.31±0.57 0.918
AFP (ng/mL) 3.4 (0.8-644.3) 3.4 (0.8-644.3) 3.4 (1.1-259.8) 0.811*
HBeAg status, n (%) 285 (56.3) 142 (56.1) 143 (56.5) 0.929#
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HBV DNA detectable (%) 351 (69.4) 182 (71.9) 169 (66.8) 0.210#
anti-HBV therapy (%) 47 (9.3) 23 (9.1) 24 (9.5) 0.878#
Fibrosis stage, n (%) 0.933#
S0 251 (49.6) 123 (48.6) 128 (50.6)
S1 167 (33.0) 84 (33.2) 83 (32.8)
S2 48 (9.5) 26 (10.2) 22 (8.7)
S3 22 (4.3) 10 (4.0) 12 (4.7)
S4 18 (3.6) 10 (4.0) 8 (3.2)
WBC, white blood cell; RBC, red blood cell; Hgb, hemoglobin; RDW, red cell distribution width;
PLT, platelet count; TP, total protein; ALB, albumin; TBIL, total bilirubin; AST, aspartate
aminotransferase; ALT, alanine aminotransferase; GGT, gamma glutamyl transpeptidase; ALP,
alkaline phosphatase; FPG, fasting plasma glucose; TG, triglyceride; Tch, total cholesterol; INR,
the international normalized ratio; PT, prothrombin time; APTT, activated partial thromboplastin
time; AFP, alpha fetal protein. P values are comparisons between the estimation cohort and
validation cohort using independent samples t-test, except: #: using Chi-squared test, *: using
Mann-Whitney U test.
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Table 3. Variables Associated with Significant Fibrosis in the Estimation Cohort
Variable S0-1 (n=207) S2-4 (n=46) P value
Age (years) 37.2±9.8 38.9±10.8 0.288
Male, n (%) 132 (63.8) 34 (73.9) 0.190#
BMI (kg/m2) 22.6±3.26 22.2±4.28 0.316
WBC (109/L) 5.46±1.49 5.53±2.10 0.773
RBC (1012
/L) 4.81±0.50 4.76±0.59 0.536
Hgb (g/L) 148±19 144±19 0.238
RDW (%) 13.0±1.1 13.5±1.5 0.021
PLT (109/L) 189±53 150±55 <0.001
TP (g/L) 73.1±6.3 70.0±7.7 0.006
ALB (g/L) 45.9±4.8 42.5±6.2 <0.001
TBIL (µmol/L) 13 (4-69) 14 (4-436) 0.857*
AST (U/L) 30 (14-429) 31 (16-479) 0.458*
ALT (U/L) 45 (8-379) 40 (8-569) 0.759*
GGT (U/L) 24 (7-175) 37 (10-586) <0.001*
ALP (U/L) 68 (29-169) 75 (36-184) 0.044*
FPG (mmol/L) 4.60±0.52 4.83±1.77 0.159
TG (mmol/L) 1.03 (0.42-9.41) 0.88 (0.39-2.88) 0.032*
Tch (mmol/L) 4.62±0.95 3.79±1.10 <0.001
INR 1.00±0.07 1.12±0.4 <0.001
PT (s) 11.5±0.8 12.9±4.4 <0.001
APTT (s) 27.4±4.3 31.7±8.1 <0.001
Fbg (g/L) 2.34±0.58 2.17±0.82 0.103
AFP (ng/mL) 3.2 (1.0-20.7) 4.8 (0.8-644.3) 0.034*
HBeAg status, n (%) 117 (56.5) 25 (54.3) 0.788#
WBC, white blood cell; RBC, red blood cell; Hgb, hemoglobin; RDW, red cell distribution width;
PLT, platelet count; TP, total protein; ALB, albumin; TBIL, total bilirubin; AST, aspartate
aminotransferase; ALT, alanine aminotransferase; GGT, gamma glutamyl transpeptidase; ALP,
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alkaline phosphatase; FPG, fasting plasma glucose; TG, triglyceride; Tch, total cholesterol; INR,
the international normalized ratio; PT, prothrombin time; APTT, activated partial thromboplastin
time; AFP, alpha fetal protein. P values are of comparisons between S0-1 and S2-4 using
independent samples t-test, except: #: using Chi-squared test, *: using Mann-Whitney U test.
Table 4. Area under curve of AA and Other Non-invasive Indices in the Estimation Cohort
Index All patients Patients with ALT< 2×ULN Patients with HBeAg negative
AUC (95% CI) SE AUC (95% CI) SE AUC (95% CI) SE
AA 0.822 (0.714-0.930)* 0.055 0.845
(0.718-0.971)*
0.064 0.893 (0.779-0.999) * 0.058
AAR 0.554 (0.411-0.697) 0.073 0.566 (0.406-0.727) 0.082 0.638 (0.447-0.829) 0.098
FIB-4 0.691 (0.555-0.827)* 0.070 0.643 (0.470-0.815) 0.088 0.614 (0.398-0.829) 0.110
Forns 0.687 (0.554-0.820)* 0.068 0.690
(0.534-0.847)*
0.080 0.636 (0.417-0.856) 0.112
APRI 0.707 (0.579-0.834)* 0.065 0.690
(0.546-0.835)*
0.074 0.685 (0.484-0.886) 0.103
Fibro Q 0.661 (0.517-0.804)* 0.073 0.667
(0.494-0.839)*
0.088 0.675 (0.469-0.882) 0.105
APGA 0.758 (0.635-0.881)* 0.063 0.748
(0.605-0.892)*
0.073 0.695 (0.502-0.887) 0.098
PAPAS 0.630 (0.491-0.769) 0.071 0.621 (0.462-0.781) 0.081 0.565 (0.344-0.786) 0.113
GUCI 0.729 (0.607-0.851)* 0.062 0.719
(0.583-0.855)*
0.069 0.714 (0.521-0.908) * 0.099
RPR 0.723 (0.589-0.858)* 0.069 0.703
(0.531-0.875)*
0.088 0.682 (0.466-0.897) 0.110
GP 0.671 (0.526-0.817)* 0.074 0.710
(0.546-0.874)*
0.084 0.685 (0.476-0.894) 0.107
AUC: area under curve, 95% CI: 95% confidence interval, SE: standard error, * : P < 0.05.
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Table 5. Four stage systems for chronic hepatitis fibrosis stages Fibrosis
stage
Scheuer stages Ishak stages Metavir stages Xi’an stages
0 No fibrosis No fibrosis No fibrosis No fibrosis
1 Enlarged, fibrotic
portal tracts
Portal fibrosis,
with or without
short fibrous septa
Portal fibrosis
without septa
fibrosis confined to
portal tracts, periportal
spaces, and
perisinusoidal spaces
2 Periportal or
portal-portal
septa, but intact
architecture
Fibrous septa portal fibrosis
with rare septa
bridging fibrosis, with
fibrous septa
3 Fibrosis with
architectural
distortion, but no
obvious cirrhosis
Transition to
cirrhosis
portal fibrosis
with many
septa
a lot of fibrous septa
separate without
obvious cirrhosis
4 Probable or
definite cirrhosis
Probable or
definite cirrhosis
cirrhosis early cirrhosis
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27x11mm (300 x 300 DPI)
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37x12mm (300 x 300 DPI)
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STARD checklist for reporting of studies of diagnostic accuracy
(version January 2003)
Section and Topic Item
#
On page #
TITLE/ABSTRACT/
KEYWORDS
1 Identify the article as a study of diagnostic accuracy (recommend MeSH
heading 'sensitivity and specificity').
1-2
INTRODUCTION 2 State the research questions or study aims, such as estimating diagnostic
accuracy or comparing accuracy between tests or across participant
groups.
4
METHODS
Participants 3 The study population: The inclusion and exclusion criteria, setting and
locations where data were collected.
5
4 Participant recruitment: Was recruitment based on presenting symptoms,
results from previous tests, or the fact that the participants had received
the index tests or the reference standard?
5
5 Participant sampling: Was the study population a consecutive series of
participants defined by the selection criteria in item 3 and 4? If not,
specify how participants were further selected.
5
6 Data collection: Was data collection planned before the index test and
reference standard were performed (prospective study) or after
(retrospective study)?
5-6
Test methods 7 The reference standard and its rationale. 6-7
8 Technical specifications of material and methods involved including how
and when measurements were taken, and/or cite references for index
tests and reference standard.
9 Definition of and rationale for the units, cut-offs and/or categories of the
results of the index tests and the reference standard.
5-8
10 The number, training and expertise of the persons executing and reading
the index tests and the reference standard.
5
11 Whether or not the readers of the index tests and reference standard
were blind (masked) to the results of the other test and describe any
other clinical information available to the readers.
7
Statistical methods 12 Methods for calculating or comparing measures of diagnostic accuracy,
and the statistical methods used to quantify uncertainty (e.g. 95%
confidence intervals).
8
13 Methods for calculating test reproducibility, if done. no
RESULTS
Participants 14 When study was performed, including beginning and end dates of
recruitment.
8-9,table 2
15 Clinical and demographic characteristics of the study population (at least
information on age, gender, spectrum of presenting symptoms).
table 2
16 The number of participants satisfying the criteria for inclusion who did or
did not undergo the index tests and/or the reference standard; describe
why participants failed to undergo either test (a flow diagram is strongly
recommended).
55
Test results 17 Time-interval between the index tests and the reference standard, and
any treatment administered in between.
8-9,table 2
18 Distribution of severity of disease (define criteria) in those with the target
condition; other diagnoses in participants without the target condition.
9
19 A cross tabulation of the results of the index tests (including
indeterminate and missing results) by the results of the reference
standard; for continuous results, the distribution of the test results by the
results of the reference standard.
9-10, table
2
20 Any adverse events from performing the index tests or the reference
standard.
no
Estimates 21 Estimates of diagnostic accuracy and measures of statistical uncertainty
(e.g. 95% confidence intervals).
9-11
22 How indeterminate results, missing data and outliers of the index tests
were handled.
no
23 Estimates of variability of diagnostic accuracy between subgroups of
participants, readers or centers, if done.
10
24 Estimates of test reproducibility, if done. no
DISCUSSION 25 Discuss the clinical applicability of the study findings. 12-17
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A novel noninvasive index using AFP and APTT is associated with liver fibrosis in patients with chronic hepatitis B
infection: A retrospective cohort study
Journal: BMJ Open
Manuscript ID: bmjopen-2015-008032.R1
Article Type: Research
Date Submitted by the Author: 18-Aug-2015
Complete List of Authors: Feng, Limin; The First Affiliated Hospital, College of Medicine, Zhejiang University, Laboratory Medicine Sun, Ke; The First Affiliated Hospital, College of Medicine, Zhejiang
University, Pathology Zhang, Jie; The First Affiliated Hospital, College of Medicine, Zhejiang University, Laboratory Medicine Feng, Guofang; Women’s Hospital, School of Medicine, Zhejiang University, Reproductive Endocrinology Zhao, Ying; The First Affiliated Hospital, College of Medicine, Zhejiang University, Laboratory Medicine
<b>Primary Subject Heading</b>:
Diagnostics
Secondary Subject Heading: Gastroenterology and hepatology, Infectious diseases
Keywords: HISTOPATHOLOGY, Hepatology < INTERNAL MEDICINE, INFECTIOUS DISEASES
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1
A novel noninvasive index using AFP and APTT is associated with liver fibrosis 1
in patients with chronic hepatitis B infection: A retrospective cohort study 2
Limin Feng1, Ke Sun
2, Jie Zhang
1, Guofang Feng
3, Ying Zhao
1* 3
4
5 1Department of Laboratory Medicine, The First Affiliated Hospital, College of 6
Medicine, Zhejiang University, Hangzhou 310003, China 7
2Department of Pathology, The First Affiliated Hospital, College of Medicine, 8
Zhejiang University, Hangzhou 310003, China 9
3Department of Reproductive Endocrinology, Women’s Hospital, School of Medicine, 10
Zhejiang University, Hangzhou 310006, China 11
12
*Corresponding author: Ying Zhao 13
Department of Laboratory Medicine, The First Affiliated Hospital, College of 14
Medicine, Zhejiang University, Qingchun Road 79#, Hangzhou 310003, China 15
E-mail: [email protected] 16
Tel.: +86-571-87236380 17
Fax: +86-571-87236383 18
19
Short title: a novel non-invasive index and liver fibrosis 20
21
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Abstract 22
Objective: A liver biopsy is the “reference standard” for diagnosing and staging liver 23
fibrosis but with many disadvantages. Therefore, developing non-invasive index for 24
predicting fibrosis is very valuable. We developed and validated a novel non-invasive 25
index for predicting significant fibrosis in patients with chronic hepatitis B infection. 26
Design: A retrospective cohort study. 27
Setting: Chronic Hepatitis B virus infected patients were recruited in the Department 28
of Infectious Disease in the First Affiliated Hospital of Zhejiang University. 29
Participants: A total of 506 patients were enrolled, and patients were randomly 30
divided into estimation (n=253) and validation (n=253) cohorts. 31
Primary and secondary outcome measures: Chronic Hepatitis B virus infected 32
patients were studied retrospectively using routine parameters. A novel index was 33
developed from an estimation cohort and validated in another cohort. Liver histology 34
was assessed for fibrosis according to Xi’an Meeting Scoring System. The novel 35
index using AFP and APTT (denoted AA index) was compared with ten other indices 36
using receiving operating characteristics curves. Multivariate forward stepwise 37
regression analysis revealed that alpha fetal protein and activated partial 38
thromboplastin time were significantly associated with the Xi’an Meeting Scoring 39
System, and were used to calculate the AA index (Log index = - 9.164 + 0.114 × AFP 40
+ 0.236 × APTT). 41
Results: The AA index predicted significant fibrosis with an area under the curve of 42
0.822, exhibited a significantly higher area compared to the other ten indices in 43
estimation cohort, and was validated in the validation cohort. 44
Conclusions: The AA index can be used to predict significant fibrosis, and may 45
decrease the need of liver biopsy in patients with chronic hepatitis B infection. 46
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Keywords: Chronic Hepatitis B virus; non-invasive index; liver biopsy; Xi’an 47
Meeting Scoring System 48
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Strengths and limitations of this study 49
▪The AA index had an AUROC curve of 0.822, 0.845, and 0.893 respectively for all 50
patients, patients with ALT <2×ULN, and patients with HBeAg negative for 51
predicting significant fibrosis. 52
▪The AA index exhibited a significantly higher AUROC for the prediction of 53
significant fibrosis compared with some non-invasive Indices. 54
▪According to the cutoff values of 0.007 and 0.127, the presence of significant fibrosis 55
was predicted with high sensitivity (90.5%) and high specificity (88.2%). 56
▪Hepatic fibrosis was evaluated only using the Xi’an stages. 57
58
59
60 61
62
63
64
65
66
67
68
69
70
71
72
73
74
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5
Introduction 75
Chronic hepatitis B virus infection (CHB) poses serious public health problems, and 76
can progress to liver fibrosis, liver cirrhosis, and hepatocellular carcinoma 1
. The 77
degree of liver fibrosis is an important parameter in the determination of appropriate 78
antiviral treatment and prognosis for patients with CHB 2,3
. 79
The "reference standard" for evaluating the degree of liver fibrosis is liver biopsy 3. 80
However, liver biopsy has some recognized limitations, such as its invasive nature, 81
pain, sampling error, inter-observer variability, non-dynamic evaluation of liver 82
fibrosis, and even a small risk of life-threatening complications 2,3
. Due to these 83
limitations and risks, it is desirable to investigate novel non-invasive methods to 84
evaluate liver fibrosis 4. These methods include biological approaches based on serum 85
biomarkers of fibrosis and physical approaches based on the measurement of liver 86
stiffness using transient elastography 3. In recent years, some non-invasive indices 87
based on routine serum biomarkers have been demonstrated to have high diagnostic 88
accuracy and cost-effectiveness in identifying significant fibrosis and cirrhosis in 89
patients with CHB and/or hepatitis C 5,6
. 90
The aim of this study was to develop a novel predictive index based on routine 91
parameters for predicting significant fibrosis according the Xi’an Meeting Scoring 92
System 7 in patients with CHB. The diagnostic performance of the new index was 93
then compared with that of several indirect non-invasive indices, including AST to 94
ALT ratio (AAR) 8, AST to platelet ratio index (APRI)
9, Forns index
10, platelet count 95
(PLT), age, AST, and INR index (FIB-4) 11
, fibro-quotient (Fibro Q)12
, AST, platelet, 96
GGT, and AFP index (APGA) 13
, Platelet, Age, Phosphatase, AFP, and AST index 97
(PAPAS) 14
, Göteborg University Cirrhosis Index (GUCI) 15
, RDW to platelet ratio 98
(RPR) 16
, and Globulin-platelet model (GP) 17
. 99
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Subjects and Methods 100
Subjects 101
Seven hundred eighty-seven consecutive urban and rural patients with CHB, including 102
476 male and 311 female aged 18–84 years (40.0±11.4 years) seen by the hepatology 103
specialty Department of Infectious Disease, The First Affiliated Hospital, College of 104
Medicine, Zhejiang University (China) between July 2010 and December 2013 were 105
considered for inclusion in the study if they had received liver biopsy and a fasting 106
serum sample collected on their first admission. A diagnosis of CHB infection 107
required a previous history of hepatitis B or hepatitis B surface antigen (HBsAg) 108
positivity for >6 months, and persistently positive HBsAg and/or hepatitis B virus 109
(HBV) DNA 18
. Exclusion criteria included age under 18 years, concurrent infection 110
with hepatitis C virus, hepatitis D virus, hepatitis G virus, and/or human 111
immunodeficiency virus, any autoimmune liver disease, hepatocellular carcinoma, 112
metabolic liver disease, alcoholic liver disease (20 grams per day for females, 30 113
grams per day for males), liver transplantation, and decompensated cirrhosis. Two 114
hundred eighty one patients were excluded because the above reasons. Finally, 506 115
patients (337 male and 169 female, 37.45±9.60years) were enrolled retrospectively. 116
Written consent was obtained prior to liver biopsy, and the trial was approved by the 117
Ethics Committee of the First Affiliated Hospital, College of Medicine, Zhejiang 118
University, China. After receiving a liver biopsy (as described below), the cohort was 119
randomly divided into estimation (n=253) and validation (n=253) cohorts for 120
derivation of the prediction model for significant fibrosis and subsequent validation 121
(Figure 1). 122
Data Collection 123
Patient demographics and laboratory parameters were recorded on the first admission. 124
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These included age, gender, HBsAg and HBeAg status, HBV DNA levels, alanine 125
aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), 126
triglyceride (TG), total cholesterol (Tch), total protein (TP), albumin (ALB), alkaline 127
phosphatase (ALP), gamma glutamyl transpeptidase (GGT), fasting plasma glucose 128
(FPG), alpha fetal protein (AFP), activated partial thromboplastin time (APTT), 129
D-dimers, fibrinogen, prothrombin time (PT), hemoglobin (Hgb), red cell distribution 130
width (RDW), White blood cell (WBC), Red blood cell (RBC), and platelet count 131
(PLT). The upper limit of normal (ULN) of ALT was 40 U/L in men and 35 U/L in 132
women. The real-time fluorescent polymerase chain reaction system (7300; Applied 133
Biosystems, Inc., Carlsbad, CA, USA) was used to detect HBV DNA levels, with a 134
lower limit of detection of 20 IU/ml. The ALT, AST, TBIL, TG, Tch, TP, ALB, ALP, 135
GGT, and FPG levels were measured on a Hitachi 7600 automatic biochemical 136
analyzer (Hitachi Ltd., Tokyo, Japan) using Roche Diagnostics GmbH reagents 137
(Roche Diagnostics, Mannheim, Germany). HBsAg, HBeAg, and AFP levels were 138
measured on an Architect Ci8200 automated immunoassay analyzer (Abbott 139
Laboratories, Abbott Park, IL, USA) using Abbott reagents. APTT, PT, and Fbg were 140
measured by a coagulation method using a Sysmex CA7000 system (Sysmex, Kobe, 141
Japan) and Siemens reagents (Siemens, Marburg, Germany) 19,20
. WBC, RBC, and 142
PLT count was assessed using a Sysmex XE-2100 automated hematology analyzer 143
(Sysmex Corp, Kobe, Japan) using Sysmex reagents. 144
Liver biopsy 145
Liver biopsy enables the reliable diagnosis of hepatic lesions, and is an important aid 146
to treatment and prognosis. For patients with HBV, liver biopsy is used for grading, 147
staging, exclusion of comorbidities, evaluation of the degree of fibrosis and/or 148
inflammation and is an important factor in the choice of an antiviral treatment strategy 149
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21. The indications for liver biopsy in the current study were: viral hepatitis, 150
autoimmune hepatitis, cholestatic liver diseases, storage diseases and metabolic 151
diseases, acute liver failure, liver transplantation, tumor, and hepatopathy of unknown 152
cause 21
. All patients underwent percutaneous liver biopsy guided by ultrasonography. 153
Liver biopsy was performed using 18G BioPince biopsy needles (InterV-MDTech, 154
Gainesville, Florida). A minimum of 1.5 cm of liver tissue with at least 5 portal tracts 155
was required for appropriate diagnosis. The specimens were fixed, paraffin-embedded, 156
and stained with hematoxylin and eosin (HE). The histologic staging of liver fibrosis 157
(S0 to S4) of liver biopsy specimens were analyzed according to the Xi’an Meeting 158
Scoring System 7 by a single pathologist who was unaware of patient characteristics. 159
Hepatic fibrosis was assessed using the Xi’an Meeting Scoring System as follows: S0, 160
no fibrosis; S1, fibrosis confined to portal tracts, periportal spaces, and perisinusoidal 161
spaces, or fibrous scar in the hepatic lobule; hepatic lobular structure integrity; S2, 162
bridging fibrosis, mainly caused by bridging necrosis; most of hepatic lobular 163
structure integrity; S3, a lot of fibrous septa are separated and/or involve the hepatic 164
lobule with distortion of the lobular structure, but without obvious cirrhosis; possible 165
with portal hypertension and esophageal varices; S4, early cirrhosis, liver parenchyma 166
is damaged extensively, with diffuse fiber hyperplasia, liver cells are in various 167
degrees of regeneration, and false flocculus is formed 7. S0 and S1 were considered to 168
indicate no fibrosis, while S2, S3, and S4 were considered to indicate significant liver 169
fibrosis. 170
Published Non-invasive Indices for Predicting Significant Liver Fibrosis 171
Some published non-invasive indices for significant fibrosis were calculated for each 172
patient based on previously described formulas, which have been summarized in 173
Table 1. The indices included AAR 8, APRI
9, Forns index
10, FIB-4
11, FibroQ
12, 174
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APGA index 13
, PAPAS index 14
, GUCI 15
, RPR 16
, and GP 17
. 175
Statistical Analysis 176
Statistical analysis was performed using SPSS16.0 (SPSS Inc., IL, USA) and 177
MedCalc v.9.3 software (MedCalc, Mariakerke, Belgium). Data are presented as 178
mean ± SD or median (range), and categorical data are presented as percentages. For 179
continuous variables, the differences between two groups were assessed with an 180
independent samples t-test or the Mann-Whitney U test, as appropriate. Categorical 181
variables were analyzed using the chi-square test. Spearman's rank correlation test 182
was used for correlation analysis. Multivariate forward stepwise regression analysis 183
was used to assess the association between the clinical/ laboratory parameters and the 184
Xi’an Meeting Scoring System fibrosis stages and to develop an index for predicting 185
significant fibrosis. A predictive index was constructed by modeling the values of 186
independent variables and their coefficient of regression. The receiver operating 187
characteristic (ROC) curve was used to assess the diagnostic performance of the novel 188
index. Differences between the diagnostic performance of the novel index and other 189
non-invasive indices were compared by using ROC curves, and the area under the 190
ROC curves (AUROC). Statistical significance was defined at two sides as P<0.05. 191
192
Results 193
Baseline Characteristics of the Patients 194
The enrolled CHB patients were divided into two cohorts: the estimation cohort and 195
the validation cohort. The demographic, laboratory and histological characteristics of 196
the estimation cohort, validation cohort, and entire cohort are shown in Table 2. There 197
were no significant differences in demographic and laboratory parameters between the 198
estimation and validation cohorts, except that the ALT levels were significantly 199
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higher in estimation cohort than those in the validation cohort. 200
Development of a Novel Index for Predicting Significant Fibrosis 201
The relevant variables of the estimation cohort based on the Xi’an Meeting Scoring 202
System (S0-1 and S2-4) are shown in Table 3. The RDW, GGT, ALP, PT, APTT, and 203
AFP levels were significantly higher in S2-4 group than those in the S0-1 group, 204
while the PLT, TP, ALB, TG, and Tch levels were significantly lower. Other 205
demographic and laboratory parameters were not significantly different between the 206
S2-4 and the S0-1 groups. Among these variables, AFP (P=0.039) and APTT 207
(P<0.001) were identified as independent predictors for significant fibrosis based on 208
multivariate forward stepwise logistic regression analysis. The relationship between 209
the Xi’an Meeting Scoring System stages and AFP and APTT separately are 210
displayed in Figure 2. It was clear from Figure 2 that as the fibrosis progressed, the 211
AFP and APTT levels increased. The Spearman correlation coefficient for AFP and 212
APTT, and the Xi’an Meeting Scoring System stages (Xi’an stages) were 0.305 213
(P=0.001) and 0.289 (P<0.001), respectively. A novel index (denoted the AA index) 214
for predicting significant fibrosis was constructed and expressed by a formula 215
consisting of AFP and APTT: 216
Log index = - 9.164 + 0.114 × AFP + 0.236 × APTT. 217
The chi-square Hosmer Lemershore test was 4.215 (P=0.837), and the Spearman 218
correlation coefficient for the new index and Xi’an stages was 0.416 (P<0.001). 219
Diagnostic Performance of the AA Index 220
The diagnostic performance of the AA index for predicting significant fibrosis was 221
assessed using the ROC curve. It was found that the AA index had an AUROC curve 222
of 0.822 (standard error (SE) =0.055; 95% CI, 0.714–0.930; P<0.001) for predicting 223
significant fibrosis in the estimation cohort. 224
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The AA index was compared with ten other published non-invasive indices, as shown 225
in Table 1. The AA, FIB-4, APRI, Forns, Fibro Q, APGA, GUCI, RPR, and GP 226
indices were all correlated with significant fibrosis (r=0.465, 0.247, 0.229, 0.253, 227
0.182, 0.367, 0.261, 0.272, and 0.253, respectively [all P<0.05]) in the estimation 228
cohort, except AAR (r=0.039, P=0.566) and PAPAS (r=0.183, P=0.063). The 229
AUROC of the AA and other indices for predicting significant fibrosis in all patients, 230
patients with ALT levels lower than the 2-fold ULN (ALT< 2×ULN), and patients 231
with hepatitis B e antigen (HBeAg) negativity in the estimation cohort are shown in 232
Table 4. The ROC curves for AA and these ten indices for all patients, patients with 233
ALT< 2×ULN, and HBeAg negative patients are shown in Figures 3a, 3b and 3c, 234
respectively. The AA index exhibited a significantly higher AUROC for the 235
prediction of significant fibrosis compared to AAR (P=0.003) and PAPAS (P=0.033). 236
No significant differences were observed between the AUROCs of FIB-4 (P=0.141), 237
Forns (P=0.123), APGA (P=0.444), GP (P=0.101), APRI (P=0.177), Fibro Q 238
(P=0.078), GUCI (P=0.262), and RPR (P=0.262) indices and AA index in the 239
prediction of significant fibrosis. 240
Definition Cut-off Values 241
We selected low (0.007) and high (0.127) cutoff values that achieved an excess of 242
90% for both sensitivity and specificity in the diagnosis of significant fibrosis in the 243
estimation cohort. The sensitivity, specificity, positive predictive value (PPV), 244
negative predictive value (NPV), positive likelihood ratio (+LR), and negative 245
likelihood ratio (-LR) of AA are shown in Table 5. 246
Validation Cohort 247
Applying the new AA index to the validation cohort, the AUROC for predicting 248
significant fibrosis was 0.773 (SE=0.053; 95% CI, 0.669–0.877; P<0.001). The 249
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AUROC in the total cohort was 0.795 (SE=0.038; 95% CI, 0.720–0.871; P<0.001). 250
There were no significant differences in the AUCs between the estimation and 251
validation cohorts (Z=0.642, P=0.521). The AA, FIB-4, APRI, Forns, Fibro Q, APGA, 252
PAPAS, GUCI, RPR, and GP indices all correlated well with significant fibrosis 253
(r=0.358, 0.247, 0.271, 0.285, 0.168, 0.323, 0.211, 0.291, 0.274, and 0.256, 254
respectively [all P<0.05]) in validation cohort, except AAR (r=-0.023, P=0.736). The 255
AUROCs of AAR, FIB-4, APRI, Forns, Fibro Q, APGA, PAPAS, GUCI, RPR, and 256
GP indices were 0.412, 0.670, 0.707, 0.708, 0.592, 0.745, 0.672, 0.722, 0.689, and 257
0.716, respectively. The AA index exhibited a significantly higher AUC in the 258
prediction of significant fibrosis compared to AAR (P<0.001) and Fibro Q (P=0.008). 259
No significant difference was observed between the AUROCs of FIB-4 (P=0.079), 260
Forns (P=0.154), APGA (P=0.366), GP (P=0.209), APRI (P=0.181), PAPAS 261
(P=0.113), GUCI (P=0.249), and RPR (P=0.132) indices and the AA index in the 262
prediction of significant fibrosis. The AUROCs of AA, AAR, FIB-4, APRI, Forns, 263
Fibro Q, APGA, PAPAS, GUCI, RPR, and GP indices were 0.792, 0.187, 0.448, 264
0.556, 0.606, 0.390, 0.683,0.564, 0.633, 0.579, and 0.595, respectively, for HBeAg 265
negative patients, and were 0.762, 0.407, 0.665, 0.696, 0.677, 0.618, 0.698, 0.570, 266
0.692, 0.693, and 0.698, respectively, for patients with ALT< 2×ULN. According to 267
the cutoff values of 0.007 and 0.127, the presence of significant fibrosis was predicted 268
with high sensitivity (90.5%) and high specificity (88.2%) in the validation cohort 269
(Table 5). 270
271
Discussion 272
Many studies have indicated that non-invasive indices containing simple serum 273
markers are valuable in the evaluation of liver fibrosis in patients with chronic liver 274
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diseases 8-17
. Most of the non-invasive methods were developed in patients with 275
chronic hepatitis C (CHC) virus infections 9-12,15
. In recent years, these indices have 276
been used to evaluate CHB patients 13,14,16,17
. In CHB, evaluation of liver fibrosis is 277
crucial since HBV cannot be eradicated completely from the patient by treatment for 278
the persistence of covalently closed circular DNA in the nucleus of infected 279
hepatocytes 22,23
. European Association for the Study of the Liver (EASL) guidelines 280
have stated that non-invasive evaluation of fibrosis would be of interest in CHB 24
. 281
Although these methods cannot replace liver biopsy in chronic liver diseases, they 282
narrow the group who really need biopsy and provide an evaluation of liver damage 283
without biopsy 24
. Many clinicians have already used these tests for patients with 284
CHB in the same way as for CHC 21
. 285
The AA index was based on two routine serum parameters: AFP and APTT. The 286
Spearman correlation found AFP and APTT were significantly correlated with the 287
Xi’an stages. The addition of other variables in our study did not further improve the 288
accuracy of the index. AFP has been shown in previous studies to be associated with 289
significant fibrosis in CHB 13,14,17,25,26
. AFP is related to hepatic impairment and 290
chronic fibrosis and can aid in the differential diagnosis of hepatic diseases 25
. APTT 291
measures the intrinsic pathway of coagulation, and the APTT values are in accordance 292
with the fact that the degree of impairment of clotting factors is related to the severity 293
of liver damage 27
. There were some non-routine parameters used in some indices for 294
predicting fibrosis, including hyaluronic acid, a-2 macroglobulin, haptoglobin, 295
apolipoprotein A1, and Golgi protein 73, however, use of these parameters in 296
predictive models might hinder widespread use of these indices 22,25,28,29
. 297
Liver biopsy also has its limitations and the AUROC cannot be compared without 298
particular care that of other studies when the prevalence of the different stage of 299
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fibrosis are not the same. The AUROC in evaluating non-invasive indices of fibrosis 300
never reached a perfect value of 1.0, and barely reached 0.90 30,31
. Indices such as 301
FIB-4, GUCI, APRI, FibroQ, and Forns were developed based on patients with CHC 302
9-12,15, while APGA, PAPAS, RPR, and GP indices were developed based on patients 303
with CHB 13,14,16,17
. Even with using the same indices, a different study population 304
will lead to different results; only the APGA, RPR, and GP indices were based on a 305
Chinese population. The AUROC of FIB-4, GUCI, APRI, Fibro Q, and Forns indices 306
for CHB patients in our estimation cohort and in our validation cohort were all lower 307
than those of previous studies with CHC patients 9-12,15
. A study by Erdogan et al. 32
308
also evaluated the AUROC of FIB-4, GUCI, APRI, FibroQ, and Forns indices in 309
CHB patients and found that the AUROC was lower than those in CHC patients 9-12,15
, 310
which is similar to the current results. The pathogenesis of liver fibrosis in CHB is 311
different from that of CHC 33-36
. First, the total amount of liver fibrosis reflected by 312
the fibrosis area is significantly lower in CHB than in CHC 34
. Second, hepatitis B 313
patients tend to progress to cirrhosis with larger nodules (macronodular cirrhosis) than 314
hepatitis C patients 34
. Third, bridging necrosis is the main pathogenic predictors of 315
fibrosis progression in CHB. However, CHC has a more progressive natural history 316
with persistent inflammation associated with liver fibrosis and cirrhosis 33
. Fourth, 317
hepatic stellate cells (HSCs) have a key role in the development of fibrosis in chronic 318
liver disease, and activated HSCs synthesize and secrete chemokines, extracellular 319
matrix proteins, and other factors, which all contribute to remodel liver fibrosis 35,36
. 320
HBV Dane particles and X and C protein may induce HSC proliferation through the 321
platelet-derived growth factor-B/PDGF receptor-β signal pathway 36
. However, HCV 322
core protein may directly activate hepatic fibrogenesis a by a toll-like receptor 323
2-dependent manner 35
. Fifth, the liver biopsies in these studies were assessed for 324
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fibrosis stages according to different staging systems 9-12,14-16
, except that APGA was 325
based on liver stiffness measurements13
. The Scheuer 10
, Ishak 9,14,15
, and METAVIR 326
11,12,16 staging systems are often used in clinical pathology, but the Xi’an stages
7 are 327
widely used in China. These staging systems all have advantages and disadvantages 37
. 328
A comparison of the four staging systems for chronic hepatitis fibrosis stages are 329
listed in Table 6; the selection of staging system depends on the comfort of the 330
pathologist and the needs of the involved clinicians 37,38
. Compared with FIB-4, GUCI, 331
APRI, FibroQ, and Forns, which were developed based on patients with CHC by 332
ROC analyses 9-12,15
, the AA index is more suitable for patients with CHB, FIB-4, 333
GUCI, APRI, FibroQ; Forns is more suitable for patients with CHC. The APGA, 334
PAPAS, RPR, and GP indices were developed based on patients with CHB 13,14,16,17
. 335
However, the APGA was based on liver stiffness measurements, and not on liver 336
biopsy, and the study population of the PAPAS index was not Chinese. 337
Defects in the design of diagnostic studies include problems with the study population 338
and bias. Despite the fact that ROC analysis is widely used in diagnostic test 339
evaluations, a proper design with a broad study population and avoidance of bias are 340
required to obtain valid and reliable conclusions in the assessment of diagnostic test 341
evaluations 39
. A broad study population is required to evaluate the accuracy and 342
specificity. Bias can manifest in many different ways, including different diagnosis 343
procedures and a non-blind design. Bias can lead to a false low or high 344
sensitivity/specificity and, therefore, a false low or high AUC 39
. In the current study, 345
we included varying degrees of fibrosis (S0-S4). Although the 346
prevalence of severe fibrosis (S4) was low, hepatic fibrosis was assessed using the 347
Xi’an staging system, which led to a limitation in the comparison of AUCs. Low 348
(0.007, absence of fibrosis) and high (0.127, presence of fibrosis) cutoff values that 349
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achieved high sensitivity and specificity for the diagnosis of significant fibrosis were 350
selected. A clinician may choose not to perform a liver biopsy with AA index < 0.007 351
or > 0.127, avoiding biopsy associated risks and costs, and may choose clinical 352
follow-up instead. International guidelines of Chronic Hepatitis B suggest that CHB 353
patients with ALT > 2×ULN should be treated. However, recent reports have 354
suggested that CHB patients with persistently normal ALT levels may experience 355
severe histologic liver damage 29,40
. HBeAg negative CHB patients are usually 356
asymptomatic for the first 30-40 years 41
. The characteristics, therapy and prognosis 357
of HBeAg negative CHB are different from positive ones, spontaneous recovery of 358
HBeAg negative CHB is rare, and the long-term prognosis is poor with rapid 359
evolution to cirrhosis and Hepatocellular Carcinoma 41,42
. Therefore, the degree of 360
hepatic fibrosis can guide treatment decisions and monitor progress in patients with 361
ALT < 2×ULN and that are HBeAg negative 43,44
Only a few studies have addressed 362
ALT < 2×ULN and HBeAg negative CHB patients with hepatic fibrosis 43,44
. Our 363
study found that the AUCs of the AA index in our study were higher than other 364
indices, and may be useful to predict significant fibrosis in CHB patients with ALT < 365
2×ULN who are HBeAg negative. 366
The present study has several limitations. First, hepatic fibrosis was evaluated only 367
using the Xi’an stages by a single pathologist, and APPT and AFP are not available in 368
some developing countries. Second, some liver tissue had only 5 portal tracts in the 369
liver biopsy. As this is less than the recommended 11 portal tracts 45
, this is a clear 370
limitation of the current study. Third, the AA index was developed for patients with 371
CHB, and the prevalence of severe fibrosis in the Chinese CHB population was low; 372
thus, the AA index may not be applicable to patients with CHC or other causes of 373
hepatic fibrosis and other ethnic populations. Fourth, some non-routine parameters 374
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used in some indices for predicting fibrosis, including hyaluronic acid, a-2 375
macroglobulin, haptoglobin, apolipoprotein A1, and Golgi protein 73, were not 376
available for use in the current study 22,25,28,29
. Fibrotest (Fibrosure in the USA) is a 377
non-invasive index for predicting significant fibrosis in patients with CHC or CHB. 378
The laboratory parameters for calculating Fibrotest include α2-macroglobulin, 379
apolipoprotein A1, haptoglobin, γ-GT, and total bilirubin obtained on the same day as 380
liver biopsy. However, α2-macroglobulin and haptoglobin were not routinely 381
available in our hospital. Therefore, it was not possible to perform Fibrotest, and 382
compare the AUROC of the AA index for predicting significant fibrosis with that of 383
Fibrotest. The AUROC of the Fibrotest index for predicting significant fibrosis was 384
reported by Leroy et al. 22
to be 0.77 (95%CI:0.71-0.83), which was smaller than that 385
of our study. In contrast, Kim et al. 46
found the AUROC was 0.903 (0.838–0.968), 386
which was larger than that of our study. Morever, FibroScan can calculate liver 387
elasticity using a low frequency elastic wave transmitted through the liver, and has 388
been considered the most accurate non-invasive model to assess liver fibrosis among 389
patients with chronic liver diseases due to various etiologies 47
. While Fibroscan 390
certainly has value as a non-invasive measure of liver fibrosis, the instrument was not 391
available in our institution. Therefore, we were unable to compare results. Therefore, 392
we were unable to compare our index with these indices. Fifth, although the AA index 393
can be accurately used to predict significant fibrosis, it cannot truly replace 394
histological fibrosis staging. The AA index is likely to be most useful as a supplement 395
to liver biopsy. Sixth, larger sample sizes as well as multi-center and multi-ethnic 396
studies will be necessary to validate the clinical application of the AA index. These 397
non-invasive indices were used to diagnose significant fibrosis (F2) and/or cirrhosis 398
(F4) using various AUROC and cutoff values. However, we only studied a binary 399
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comparison of no fibrosis (S0, S1) versus some fibrosis (S2, S3, S4). If only a small 400
number of patients with advanced fibrosis were included in the studies, the accuracy 401
of the non-invasive indices for higher stages of fibrosis (F3 and F4) can influence the 402
validity of the serum markers investigated 5,15,16
. A small number of patients with 403
advanced fibrosis is a limitation of the current study. In conclusion, we found that an 404
index (AA) containing AFP and APTT can accurately predict significant fibrosis in 405
CHB patients with ALT< 2×ULN that are HBeAg negative. The AA index is more 406
accurate than the AAR, APRI, Forns, FIB-4, FibroQ, APGA, PAPAS, GUCI, RPR, 407
and GP indices. The parameters used in the AA index are widely available, and can be 408
used as non-invasive index to predict significant HBV-related fibrosis. Use of the AA 409
index may decrease the need of liver biopsy in patients with CHB. 410
Acknowledgments 411
We thank Medjaden Bioscience, Limited for helping in proofreading and editing the 412
manuscript. 413
414
Footnotes 415
Contributorship statement YZ and LF contributed to the study conception/design. 416
LF, KS, JZ, and GF contributed to the data collection. YZ and LF conducted the data 417
analysis, critically revised the article and reviewed the draft of the article. 418
Funding This work was supported by grants from the Department of Education 419
Foundation of Zhejiang Province, China (Nos. Y201017380 and Y201330146). The 420
funders had no role in study design, data collection and analysis, decision to publish, 421
or preparation of the manuscript. 422
Competing interests: None declared. 423
Patient consent Obtained. 424
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Ethics approval This study was approved by the ethics committee of the First 425
Affiliated Hospital of Zhejiang University School of Medicine, China. 426
Data sharing statement No additional unpublished data are available. 427
428
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Figure Legends 556
Figure 1. The flow diagram of the study. 557
558
Figure 2. Box plots displaying the values of alpha fetal protein and activated partial 559
thromboplastin time based on Xi’an Meeting Scoring System. 560
561
The top and bottom of each box represents the 25th and 75th percentile interval. The 562
line through the box in the median and the error bars are the 5th and 95th percentile 563
intervals. AFP, alpha fetal protein; APTT, activated partial thromboplastin time. 564
565
566
Figure 3. Receiver operating characteristic curves for prediction of significant fibrosis 567
in the estimation cohort using the new index in comparison with several other 568
calculated indices. 569
570
a: all patients, b: patients with ALT< 2×ULN, c: patients HBeAg negative. AA, the 571
new index consisted of alpha fetal protein and activated partial thromboplastin time; 572
ROC, receiver operating characteristic; ALT, alanine aminotransferase; ULN, upper 573
limit of normal; HBeAg, hepatitis B e antigen. 574
575
576
577
578
579
580
581
582
583
584
585
586
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587
588
589
590
Table 1. Summary of Non-invasive Indices for Predicting Significant Liver Fibrosis 591
Index Formula
AAR [8] AST/ALT
FIB-4 [11] (Age×AST)/ (PLT (109/L)×ALT
1/2]
Forns index[10] 7.811–3.131×LN(PLT)+0.781×LN(GGT)+3.467×LN(age)-0.014×Tch
APRI [9] [(AST/ULN)/PLT (109/L)] ×100
Fibro Q [12] (10×age×AST×PT INR)/(PLT×ALT)
APGA [13] Log(index)=1.44+0.1490×log(GGT)+0.3308×log(AST)-0.5846×log(PL
T)+0.1148×log (AFP+1)
PAPAS [14] Log(index+1)=0.0255+0.0031×age+0.1483×log(ALP)-0.004×log(AST)
+0.0908×log(AFP+1)-0.028×log (PLT)
GUCI [15] [(AST/ULN) ×prothrombin-INR] ×100/ PLT
RPR [16] RDW/PLT
GP [17] GLOB×100/PLT
ALT, alanine aminotransferase; AST, aspartate aminotransferase; PLT, platelet count; GGT, 592
gamma glutamyl transpeptidase; Tch, total cholesterol; INR, the international normalized ratio; 593
AFP, alpha fetal protein; ALP, alkaline phosphatase; ULN, upper limit of normal; RDW, red cell 594
distribution width; GLOB, globulin. Units of AST, ALT, GGT, and ALP: U/L; Units of age, Tch, 595
AFP, GLOB, PLT, and RDW: years, mmol/L, ng/mL, g/dL, 109/L, and %, respectively. 596
597
598
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Table 2. Baseline Characteristics of the Patients in the Estimation and Validation 599
Cohorts 600
Variable All patients
(n=506)
Estimation cohort
(n=253)
Validation cohort
(n=253)
P value
Age (years) 37.45±9.6 37.51±10.0 37.39±9.1 0.886
Male, n (%) 337 (66.6) 166 (65.6) 171 (68.0) 0.637#
BMI (kg/m2) 22.5±3.51 22.5±3.60 22.5±3.49 0.957
WBC (109/L) 5.51±1.60 5.47±1.61 5.55±1.49 0.558
RBC (1012
/L) 4.81±0.51 4.80±0.52 4.81±0.50 0.817
Hgb (g/L) 148±18 147±19 148±17 0.501
RDW (%) 13.0±1.0 13.1±1.2 13.0±0.8 0.092
PLT (109/L) 178±53 181±55 175±51 0.191
TP (g/L) 72.2±6.7 72.5±6.7 71.8±6.7 0.268
ALB (g/L) 45.4±5.2 45.2±5.2 45.6±5.1 0.482
TBIL (µmol/L) 13 (3-436) 13 (4-436) 14 (3-280) 0.748*
AST (U/L) 30 (14-479) 31 (14-479) 30 (14-358) 0.478*
ALT (U/L) 40 (8-631) 45 (8-569) 38 (10-631) 0.019*
GGT (U/L) 25 (6-586) 25 (7-586) 25 (6-456) 0.653*
ALP (U/L) 68 (22-292) 68 (29-184) 69 (22-292) 0.871*
FPG (mmol/L) 4.72±1.41 4.64±0.90 4.80±1.80 0.268
TG (mmol/L) 0.97 (0.38-9.41) 0.99 (0.39-9.41) 0.94 (0.38-7.67) 0.780*
Tch (mmol/L) 4.47±1.04 4.46±1.03 4.47±1.05 0.917
PT (s) 11.8±1.6 11.8±2.1 11.8±0.9 0.752
APTT (s) 28.2±4.8 28.2±5.4 28.2±4.2 0.952
Fbg (g/L) 2.31±0.61 2.31±0.64 2.31±0.57 0.918
AFP (ng/mL) 3.4 (0.8-644.3) 3.4 (0.8-644.3) 3.4 (1.1-259.8) 0.811*
HBeAg status, n (%) 285 (56.3) 142 (56.1) 143 (56.5) 0.929#
HBV DNA detectable (%) 351 (69.4) 182 (71.9) 169 (66.8) 0.210#
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anti-HBV therapy (%) 47 (9.3) 23 (9.1) 24 (9.5) 0.878#
Fibrosis stage, n (%) 0.933#
S0 251 (49.6) 123 (48.6) 128 (50.6)
S1 167 (33.0) 84 (33.2) 83 (32.8)
S2 48 (9.5) 26 (10.2) 22 (8.7)
S3 22 (4.3) 10 (4.0) 12 (4.7)
S4 18 (3.6) 10 (4.0) 8 (3.2)
WBC, white blood cell; RBC, red blood cell; Hgb, hemoglobin; RDW, red cell distribution width; 601
PLT, platelet count; TP, total protein; ALB, albumin; TBIL, total bilirubin; AST, aspartate 602
aminotransferase; ALT, alanine aminotransferase; GGT, gamma glutamyl transpeptidase; ALP, 603
alkaline phosphatase; FPG, fasting plasma glucose; TG, triglyceride; Tch, total cholesterol; PT, 604
prothrombin time; APTT, activated partial thromboplastin time; AFP, alpha fetal protein. P values 605
are comparisons between the estimation cohort and validation cohort using independent samples 606
t-test, except: #: using Chi-squared test, *: using Mann-Whitney U test. 607
608
609
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Table 3. Variables Associated with Significant Fibrosis in the Estimation Cohort 610
Variable S0-1 (n=207) S2-4 (n=46) P value
Age (years) 37.2±9.8 38.9±10.8 0.288
Male, n (%) 132 (63.8) 34 (73.9) 0.190#
BMI (kg/m2) 22.6±3.26 22.2±4.28 0.316
WBC (109/L) 5.46±1.49 5.53±2.10 0.773
RBC (1012
/L) 4.81±0.50 4.76±0.59 0.536
Hgb (g/L) 148±19 144±19 0.238
RDW (%) 13.0±1.1 13.5±1.5 0.021
PLT (109/L) 189±53 150±55 <0.001
TP (g/L) 73.1±6.3 70.0±7.7 0.006
ALB (g/L) 45.9±4.8 42.5±6.2 <0.001
TBIL (µmol/L) 13 (4-69) 14 (4-436) 0.857*
AST (U/L) 30 (14-429) 31 (16-479) 0.458*
ALT (U/L) 45 (8-379) 40 (8-569) 0.759*
GGT (U/L) 24 (7-175) 37 (10-586) <0.001*
ALP (U/L) 68 (29-169) 75 (36-184) 0.044*
FPG (mmol/L) 4.60±0.52 4.83±1.77 0.159
TG (mmol/L) 1.03 (0.42-9.41) 0.88 (0.39-2.88) 0.032*
Tch (mmol/L) 4.62±0.95 3.79±1.10 <0.001
PT (s) 11.5±0.8 12.9±4.4 <0.001
APTT (s) 27.4±4.3 31.7±8.1 <0.001
Fbg (g/L) 2.34±0.58 2.17±0.82 0.103
AFP (ng/mL) 3.2 (1.0-20.7) 4.8 (0.8-644.3) 0.034*
HBeAg status, n (%) 117 (56.5) 25 (54.3) 0.788#
WBC, white blood cell; RBC, red blood cell; Hgb, hemoglobin; RDW, red cell distribution width; 611
PLT, platelet count; TP, total protein; ALB, albumin; TBIL, total bilirubin; AST, aspartate 612
aminotransferase; ALT, alanine aminotransferase; GGT, gamma glutamyl transpeptidase; ALP, 613
alkaline phosphatase; FPG, fasting plasma glucose; TG, triglyceride; Tch, total cholesterol; PT, 614
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30
prothrombin time; APTT, activated partial thromboplastin time; AFP, alpha fetal protein. P values 615
are of comparisons between S0-1 and S2-4 using independent samples t-test, except: #: using 616
Chi-squared test, *: using Mann-Whitney U test. 617
618
619
Table 4. Area under curve of AA and Other Non-invasive Indices in the Estimation Cohort 620
Index All patients Patients with ALT< 2×ULN Patients with HBeAg negative
AUC (95% CI) SE AUC (95% CI) SE AUC (95% CI) SE
AA 0.822 (0.714-0.930)* 0.055 0.845
(0.718-0.971)*
0.064 0.893 (0.779-0.999) * 0.058
AAR 0.554 (0.411-0.697) 0.073 0.566 (0.406-0.727) 0.082 0.638 (0.447-0.829) 0.098
FIB-4 0.691 (0.555-0.827)* 0.070 0.643 (0.470-0.815) 0.088 0.614 (0.398-0.829) 0.110
Forns 0.687 (0.554-0.820)* 0.068 0.690
(0.534-0.847)*
0.080 0.636 (0.417-0.856) 0.112
APRI 0.707 (0.579-0.834)* 0.065 0.690
(0.546-0.835)*
0.074 0.685 (0.484-0.886) 0.103
Fibro Q 0.661 (0.517-0.804)* 0.073 0.667
(0.494-0.839)*
0.088 0.675 (0.469-0.882) 0.105
APGA 0.758 (0.635-0.881)* 0.063 0.748
(0.605-0.892)*
0.073 0.695 (0.502-0.887) 0.098
PAPAS 0.630 (0.491-0.769) 0.071 0.621 (0.462-0.781) 0.081 0.565 (0.344-0.786) 0.113
GUCI 0.729 (0.607-0.851)* 0.062 0.719
(0.583-0.855)*
0.069 0.714 (0.521-0.908) * 0.099
RPR 0.723 (0.589-0.858)* 0.069 0.703
(0.531-0.875)*
0.088 0.682 (0.466-0.897) 0.110
GP 0.671 (0.526-0.817)* 0.074 0.710
(0.546-0.874)*
0.084 0.685 (0.476-0.894) 0.107
AUC: area under curve, 95% CI: 95% confidence interval, SE: standard error, * : P < 0.05. 621
622
623
624
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625
Table 5 Diagnostic accuracy of AA index in the estimation and validation cohorts 626
cutoff S0-1 S2-4 Sensitivity (%) Specificity (%) PPV (%) NPV (%) +LR -LR
Estimation cohort (N=253) 207 46
Low cutoff 91.3(51.8-99.7) 50.0(37.8-62.2) 28.8(6.0-62.2) 96.3(86.4-99.5) 1.83(1.3-2.5) 0.17(0.03-1.2)
< 0.007 103 4
≥ 0.007 104 42
High cutoff 65.2 (29.9-92.5) 90.0(80.5-95.5) 60.0(9.4-90.6) 92.1%(82.7-96.9) 6.52(2.3-15.7) 0.39(0.1-1.3)
< 0.127 186 16
≥ 0.127 20 30
Validation cohort (N=253) 211 42
Low cutoff 90.5(51.6-97.7) 42.2(31.2-54.0) 23.8(6.5-45.5) 95.7(78.1-99.9) 1.57(0.6-9.5) 0.23(0.04-1.8)
< 0.007 89 4
≥ 0.007 122 38
High cutoff 66.7(34.9-94.1) 88.2(79.2-94.3) 52.8(0.8-90.6) 93.0(79.6-97.6) 5.65(0.5-18.2) 0.38(0.05-2.0)
< 0.127 186 14
≥ 0.127 25 28 PPV: positive predictive value, NPV: negative predictive value, +LR: positive likelihood ratio, -LR: negative likelihood ratio 627
628
629
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630
Table 6. Four stage systems for chronic hepatitis fibrosis stages 631
Fibrosis
stage
Scheuer stages Ishak stages Metavir stages Xi’an stages
0 No fibrosis No fibrosis No fibrosis No fibrosis
1 Enlarged, fibrotic
portal tracts
Portal fibrosis,
with or without
short fibrous septa
Portal fibrosis
without septa
fibrosis confined to
portal tracts, periportal
spaces, and
perisinusoidal spaces
2 Periportal or
portal-portal
septa, but intact
architecture
Fibrous septa portal fibrosis
with rare septa
bridging fibrosis, with
fibrous septa
3 Fibrosis with
architectural
distortion, but no
obvious cirrhosis
Transition to
cirrhosis
portal fibrosis
with many
septa
a lot of fibrous septa
separate without
obvious cirrhosis
4 Probable or
definite cirrhosis
Probable or
definite cirrhosis
cirrhosis early cirrhosis
632
633
634
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57x30mm (300 x 300 DPI)
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STARD checklist for reporting of studies of diagnostic accuracy
(version January 2003)
Section and Topic Item
#
On page #
TITLE/ABSTRACT/
KEYWORDS
1 Identify the article as a study of diagnostic accuracy (recommend MeSH
heading 'sensitivity and specificity').
1-2
INTRODUCTION 2 State the research questions or study aims, such as estimating diagnostic
accuracy or comparing accuracy between tests or across participant
groups.
4
METHODS
Participants 3 The study population: The inclusion and exclusion criteria, setting and
locations where data were collected.
5
4 Participant recruitment: Was recruitment based on presenting symptoms,
results from previous tests, or the fact that the participants had received
the index tests or the reference standard?
5
5 Participant sampling: Was the study population a consecutive series of
participants defined by the selection criteria in item 3 and 4? If not,
specify how participants were further selected.
5
6 Data collection: Was data collection planned before the index test and
reference standard were performed (prospective study) or after
(retrospective study)?
5-6
Test methods 7 The reference standard and its rationale. 6-7
8 Technical specifications of material and methods involved including how
and when measurements were taken, and/or cite references for index
tests and reference standard.
9 Definition of and rationale for the units, cut-offs and/or categories of the
results of the index tests and the reference standard.
5-8
10 The number, training and expertise of the persons executing and reading
the index tests and the reference standard.
5
11 Whether or not the readers of the index tests and reference standard
were blind (masked) to the results of the other test and describe any
other clinical information available to the readers.
7
Statistical methods 12 Methods for calculating or comparing measures of diagnostic accuracy,
and the statistical methods used to quantify uncertainty (e.g. 95%
confidence intervals).
8
13 Methods for calculating test reproducibility, if done. no
RESULTS
Participants 14 When study was performed, including beginning and end dates of
recruitment.
8-9,table 2
15 Clinical and demographic characteristics of the study population (at least
information on age, gender, spectrum of presenting symptoms).
table 2
16 The number of participants satisfying the criteria for inclusion who did or
did not undergo the index tests and/or the reference standard; describe
why participants failed to undergo either test (a flow diagram is strongly
recommended).
55
Test results 17 Time-interval between the index tests and the reference standard, and
any treatment administered in between.
8-9,table 2
18 Distribution of severity of disease (define criteria) in those with the target
condition; other diagnoses in participants without the target condition.
9
19 A cross tabulation of the results of the index tests (including
indeterminate and missing results) by the results of the reference
standard; for continuous results, the distribution of the test results by the
results of the reference standard.
9-10, table
2
20 Any adverse events from performing the index tests or the reference
standard.
no
Estimates 21 Estimates of diagnostic accuracy and measures of statistical uncertainty
(e.g. 95% confidence intervals).
9-11
22 How indeterminate results, missing data and outliers of the index tests
were handled.
no
23 Estimates of variability of diagnostic accuracy between subgroups of
participants, readers or centers, if done.
10
24 Estimates of test reproducibility, if done. no
DISCUSSION 25 Discuss the clinical applicability of the study findings. 12-17
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