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Clinical characteristics differ between patients with non-traumatic neck pain, patientswith whiplash-associated disorders, and pain-free individualsStenneberg, Martijn S.; Scholten-Peeters, Gwendolyne G. M.; den Uil, Carlien S.;Wildeman, Margreet E.; van Trijffel, Emiel; de Bie, Rob A.

published inPhysiotherapy Theory and Practice2021

DOI (link to publisher)10.1080/09593985.2021.1962464

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citation for published version (APA)Stenneberg, M. S., Scholten-Peeters, G. G. M., den Uil, C. S., Wildeman, M. E., van Trijffel, E., & de Bie, R. A.(2021). Clinical characteristics differ between patients with non-traumatic neck pain, patients with whiplash-associated disorders, and pain-free individuals. Physiotherapy Theory and Practice.https://doi.org/10.1080/09593985.2021.1962464

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Clinical characteristics differ between patientswith non-traumatic neck pain, patients withwhiplash-associated disorders, and pain-freeindividuals

Martijn S. Stenneberg, Gwendolyne G.M. Scholten-Peeters, Carlien S. den Uil,Margreet E. Wildeman, Emiel van Trijffel & Rob A. de Bie

To cite this article: Martijn S. Stenneberg, Gwendolyne G.M. Scholten-Peeters, Carlien S. denUil, Margreet E. Wildeman, Emiel van Trijffel & Rob A. de Bie (2021): Clinical characteristics differbetween patients with non-traumatic neck pain, patients with whiplash-associated disorders, andpain-free individuals, Physiotherapy Theory and Practice, DOI: 10.1080/09593985.2021.1962464

To link to this article: https://doi.org/10.1080/09593985.2021.1962464

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Clinical characteristics differ between patients with non-traumatic neck pain, patients with whiplash-associated disorders, and pain-free individualsMartijn S. Stenneberg a,b,d, Gwendolyne G.M. Scholten-Peeters a,c, Carlien S. den Uila, Margreet E. Wildemana, Emiel van Trijffel a,d,e, and Rob A. de Bie b,f

aSOMT University of Physiotherapy, Softwareweg, Amersfoort, The Netherlands; bCAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands; cDepartment of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Van der Boechorststraat, Amsterdam, The Netherlands; dVrije Universiteit Brussel, Department of Physiotherapy, Human Physiology and Anatomy (KIMA), Experimental Anatomy Research Department (EXAN), Laarbeeklaan, Brussel, Belgium; eZiekenhuisgroep Twente, ZGT Academy, Almelo, Netherlands; fMaastricht University, Department of Epidemiology, Maastricht, Netherlands

ABSTRACTBackground Evidence is lacking to what extent patients with Whiplash-Associated Disorders (WAD), those with non-traumatic neck pain (NTNP), and pain-free individuals differ regarding type and severity of impairments, disability, and psychological factors. Objective To compare clinical characteristics between patients with WAD, with NTNP, and pain-free indivi-duals in primary care physiotherapy. Additionally, differences between patient groups for both acute and chronic symptoms were assessed. Method A cross-sectional study was conducted including 168 patients with WAD, 336 matched patients with NTNP, and 336 pain-free individuals. Differences and prevalence rates were calculated for pain intensity, pain distribution, cervical range of motion, neck flexor muscle endurance, self-reported disability, and psychological factors. Results Patients with WAD had higher pain intensity (median 6/10 vs. 5/10 p<.01), had a wider distribution of their neck pain (p=.02), more restricted cervical flexion-extension (-11.9°) and rotation (-12.4°), less muscle endurance (-5.5 seconds), and more disability (+14.0%), compared to patients with NTNP. More patients with WAD reported low back pain (+9.5%) and headache (+12.2%) as musculoskeletal comorbidities. Regarding anxiety, depression, and stress, most patients (>83%) scored in the normal range. No significant differences between the patient groups were observed (p>.16). Both patient groups scored significantly worse than pain-free individuals on all character-istics. Patients with WAD and NTNP experienced different types of activity limitations and participa-tion restrictions. Conclusion WAD is a more severe condition than NTNP and should be considered a separate subgroup. A different approach in clinical practice and research is required for WAD and NTNP.

ARTICLE HISTORY Received 23 November 2020 Revised 19 March 2021 Accepted 19 June 2021

KEYWORDS Subgroups; cervical spine; clinical characteristics; disability; whiplash injury

Introduction

Nonspecific neck pain is a common health problem and a reason for consulting general practitioners and phy-siotherapists (Bot, 2005; Côté, Cassidy, and Carroll, 2001). It is one of the leading causes of disability worldwide (Global Burden of Disease 2017 Disease and Injury Incidence and Prevalence Collaborators, 2018; Hoy et al., 2014). Patients with nonspecific neck pain represent a heterogeneous population experiencing a variety of lim-itations such as mobility deficits, reduced cervical muscle function, disability, and higher levels of anxiety or

depression (Blanpied et al., 2017; Blozik et al., 2009; Miranda et al., 2019; Stenneberg et al., 2017; Sterling, Jull, Vicenzino, and Kenardy, 2004).

In various studies and clinical guidelines, patients with Whiplash-Associated Disorders (WAD) are considered as a separate group among patients with neck pain (Blanpied et al., 2017; Carroll et al., 2009; Sterling, 2014; Walton and Elliott, 2017; Wong et al., 2015). There is conflicting evidence as to whether, and to what extent, patients with nonspecific neck pain actually differ from WAD patients with regard to impairments, disability, and psychological

CONTACT Martijn S. Stenneberg [email protected] SOMT University of Physiotherapy, Amersfoort, Netherlands

PHYSIOTHERAPY THEORY AND PRACTICE https://doi.org/10.1080/09593985.2021.1962464

© 2021 Taylor & Francis Group, LLC

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factors (Anstey, Kongsted, Kamper, and Hancock, 2016; Schiltenwolf and Beckmann, 2013; Sterling, 2014; Verhagen et al., 2011). However, the majority of studies concluded that patients with trauma-related neck pain experience higher levels of impairments, disability, and psychological disorders than patients with non-traumatic neck pain (NTNP) (Anstey, Kongsted, Kamper, and Hancock, 2016; Chien and Sterling, 2010; Coppieters et al., 2017; Ris et al., 2017; Stenneberg et al., 2017).

Previous studies, which examined physical and psy-chological factors between patients with WAD and NTNP often did not compare groups directly, included small samples, or did not use comparable groups with respect to patient characteristics such as age, sex, or duration of symptoms (Anstey, Kongsted, Kamper, and Hancock, 2016; Stenneberg et al., 2017). Moreover, stu-dies often did not include a reference group of pain-free controls to investigate whether the observed character-istics are actually different, and to what extent (Anstey, Kongsted, Kamper, and Hancock, 2016; Ris et al., 2017; Verhagen et al., 2011). Furthermore, most studies omit the use of a conceptual or theoretical model, such as the International Classification of Functioning Disability and Health (ICF), to select the variables of interest (World Health Organization, 2001). The use of a theoretical model is useful in clinical decision- making and provides insight into the interrelationship between clinically relevant constructs. Finally, no pre-vious studies explored whether possible differences between WAD and NTNP already exist in the acute phase or whether these would develop during the course of the condition (Freeman et al., 2006; Stenneberg et al., 2017; Woodhouse and Vasseljen, 2008). Consequently, there is a lack of evidence to determine whether patients with WAD, NTNP, and pain-free individuals actually differ regarding the type and severity of impairments, disability, and psychological factors. Therefore, the pri-mary aim of this study was to compare clinical charac-teristics in terms of type and severity of impairments, disability, and psychological factors between matched groups of patients with WAD, those with NTNP, and pain-free individuals in primary physiotherapy care. In addition, we assessed the differences in these character-istics between patients with acute WAD versus acute NTNP and between patients with chronic WAD versus chronic NTNP.

Methods

Study design

A cross-sectional study was conducted using data col-lected for a multicenter cohort study including patients

with WAD, patients with NTNP, and pain-free indivi-duals. We included all WAD patients (n = 168) from the entire cohort study and matched them with NTNP patients and pain-free individuals on age, gender, and duration of symptoms in a matching ratio of 1:2:2. All participants signed informed consent. Ethical approval for the study was waived by the Central Committee on Research Involving Human Subjects (CCMO, Hague, Netherlands). The STROBE statement for cross- sectional studies was used to report the study (von Elm et al., 2007).

Participants

WAD patients and NTNP patients who received phy-siotherapy for their neck pain were recruited in approxi-mately 100 primary care physiotherapy practices in the Netherlands. Pain-free individuals were recruited from the general population and via the professional networks of the physiotherapists.

Physiotherapists checked if the participants met the eligibility criteria of the study. Patients were included if they were aged 18 years or older, had WAD grade I or II (traumatic was defined as symptoms caused by a motor vehicle collision or other mishap with an acceleration– deceleration mechanism) (Spitzer et al., 1995) or NTNP grade I or II (Guzman et al., 2009) as primary complaint, could read and understand the Dutch language, and were capable of performing the assessments. Participants reporting prior cervical spine surgery, his-tory of fractures in the cervical region, known spinal malignancy or infection, developmental spine deformi-ties, or rheumatic, systemic or neurological diseases were excluded. Pain-free individuals were a convenience sample without neck pain for at least 3 months before study participation.

Procedures

Physiotherapists with at least 2 years of clinical experi-ence and studying in a Master’s degree program in manual therapy performed the measurements according to a standardized protocol. These examiners completed two 3-h training sessions. Physiotherapists were blinded for specific study hypothesis under investigation, includ-ing the group assignment (NTNP vs. WAD).

First, the physiotherapists administered a questionnaire to assess participants’ demographics, onset of neck pain (traumatic or non-traumatic), dura-tion of current neck pain in weeks, and location and radiation of the neck pain. Subsequently, active cervical range of motion and cervical muscle endurance tests

2 M. S. STENNEBERG ET AL.

Page 5

were performed, and additional questionnaires on dis-ability and psychological factors were completed. Completion of the measurements took about 1 hour. All variables were coded, processed, and stored in a de- identified manner.

Measurements

To optimize clinical applicability, this study focused on modifiable physical factors, activity limitations, partici-pation restrictions, and psychological factors commonly gathered in physiotherapy practice, recommended in clinical guidelines, or covering the ICF components (Bier et al., 2018; Blanpied et al., 2017; Guzman et al., 2009; World Health Organization, 2001). Measurement instruments have been selected based on guideline recommendations, measurement properties, and applic-ability in clinical practice (Bier et al., 2018; Blanpied et al., 2017).

Pain

Neck pain severity was assessed using a Numerical Pain Rating Scale (NPRS) ranging from 0 (no pain) to 10 (worst pain imaginable). The NPRS has been shown to

be a usable and valid instrument with a minimal detect-able change of two points (Cleland, Childs, and Whitman, 2008; Pool et al., 2007). A body chart was used to determine the location and distribution of the neck pain (Margolis, Tait, and Krause, 1986). The upper body was divided into 12 anatomical areas. The number of the affected areas shows the distribution of the neck pain (Figure 1).

Impairments

Active cervical range of motion (aCROM) was tested in flexion-extension and rotation (left+right) using the iPhone application “3D range of motion” (Stenneberg et al., 2018). This device uses the built-in acceler-ometer, gyroscope, and magnetometer function to measure the active cervical range of motion along the x, y, and z axes. Participants were seated on a chair with a backrest. The iPhone was fastened securely on the forehead by means of an iPhone holder with a rigid Velcro strap. Participants per-formed a full cycle flexion-extension, and left and right rotation, each three times and with a 10-s inter-val between each cycle. The iPhone application has shown good concurrent validity and interrater relia-bility in patients with neck pain. The standard error of measurement (SEM) is about 5.1° to 5.8° (Stenneberg et al., 2018).

Cervical flexor muscle function was assessed by the neck flexor muscle endurance test as originally described by Harris et al (Harris et al., 2005). Participants were positioned in a supine lying position and performed a craniocervical flexion while lifting the head and hold-ing this position. The test was terminated when the participant was unable to maintain the chin tuck or the proper position of the head for more than 1 second (Domenech et al., 2011; Harris et al., 2005). Cervical flexion endurance was recorded in seconds. The inter-rater reliability was found to be moderate to good, and the SEM is about 11.5 seconds (Harris et al., 2005; Olson et al., 2006).

Disability

Global levels of activity limitations and participation restrictions were both assessed on a 5-point Likert scale (0 = not at all, 1 = mild, 2 = moderate, 3 = severe, 4 = very severe) in response to the questions, “to what extent does your neck pain limit your daily activities?,” and “to what extent does your neck pain limit your social activities?”

Neck pain-related disability was measured with the 10-item Neck Disability Index (NDI). The total score is

Figure 1. Body chart for assessing the location and distribution of the neck pain.

PHYSIOTHERAPY THEORY AND PRACTICE 3

Page 6

expressed as a percentage ranging from 0% (no disabil-ity) to 100% (total disability). The NDI has acceptable reliability and validity, and the minimal detectable change is 19% (Cleland, Childs, and Whitman, 2008; MacDermid et al., 2009; Vernon and Mior, 1991).

To provide insight into the most important activity limitations and participation restrictions of each patient, the Patient Specific Functional Scale (PSFS) was used (Stratford, 1995). Each patient was asked to identify up to five of the most important activities by which they felt restricted due to neck pain. The PSFS is applicable to a variety of clinical presentations and has been shown to be an efficient and valid measure for assessing physical functions in patients with neck pain (Westaway, Stratford, and Binkley, 1998).

Psychological factors

Depression, anxiety, and stress were assessed by the widely used short-form Distress Anxiety Stress Scales (DASS-21) which is a self-report instrument consisting of three domain-specific 7-item subscales. Each question is rated from 0 (never) to 3 (almost always). Higher scores indicate more severe mental disorder symptoms (Lovibond and Lovibond, 1995b). The DASS-21 has advantages over other instruments because it is distinc-tive in measuring stress-related symptoms, it does not require expert training to administer and it is widely used in clinical and non-clinical settings (Ng et al., 2007). Reliability and validity have been found to be sufficient (Lee, Lee, and Moon, 2019; Lovibond and Lovibond, 1995a).

Data analysis

Descriptive statistics were used to describe patient characteristics. Continuous variables were checked for normality using Q–Q plots, histograms, and Shapiro– Wilk tests (p > .05) and expressed as means (SD) or medians (IQR). In case of missing test results, patients were excluded from the analyses for that specific item.

One-way ANOVA tests and Tukey post-hoc tests for continuous variables with a normal distribution or Kruskal–Wallis tests with Dunn’s post hoc tests for ordinal data or continuous data with a violation of the normality were used to explore differences between the WAD group, NTNP group, and pain-free individuals. Post-hoc Bonferroni correction was applied for multiple comparisons.

Differences between variables that were only mea-sured in the WAD and NTNP groups were analyzed with an independent sample t-test for continuous nor-mally distributed variables, or a Mann–Whitney U-test

for ordinal data or continuous variables with a non- normal distribution. Chi-squared tests were used to test differences in dichotomous variables. Independent sample T-tests or Mann–Whitney U-tests were used to assess differences between patients with acute (<3 months) WAD versus acute NTNP and patients with chronic (≥3 months duration) WAD versus those with chronic NTNP.

Three authors (MS, CU, MW), sorted, reworded (if needed), and linked the collected PSFS data to the ICF by using the ICF linking rules of Cieza, Fayed, Bickenbach, and Prodinger (2019) and Cieza et al. (2005) in a consensus meeting. As a result, a top 15 items list of most problematic activity limitations or participation restrictions due to neck pain was created for the WAD and NTNP groups, separately. The level of significance was set at α = 0.05. Statistical analyses were performed using SPSS version 25.0 (SPSS Inc., Chicago, Illinois, USA).

Results

In total, we included 168 WAD patients, 336 NTNP patients, and 336 pain-free controls. The mean age of participants was 41.3 (SD 13.1) years, 73.8% was female, and the median duration of neck pain was 13 weeks (Table 1). Less than 1% of the data were missing.

Patient groups scored worse on all variables com-pared to the pain-free control group (p < .01). Patients with WAD reported a significantly higher pain score (median 6, IQR 4–7) than those with NTNP (median 5, IQR 3–6), and also a wider distribution of their neck pain (median 4 versus 3 areas). More patients with WAD reported low back pain (+9.5%) and headache (+12.2%) as musculoskeletal comorbidities.

On cervical flexion-extension and rotation, the WAD group scored on average 11.9° (95% CI 7.6°-16.2°) and 12.4° (95% CI 7.8°-17.0°), respectively, lower than the NTNP group (p < .01) Median score on neck flexor muscle endur-ance was 25.0 seconds (IQR 16–38) for the WAD group and 30.5 seconds (IQR 21–46) for the NTNP group (p < .01).

Furthermore, patients with WAD scored signifi-cantly higher on activity limitations, participation restrictions, and disability. Prevalence of anxiety, depression, and stress, was low and no differences between patient groups were found; 13.0% of the patients with WAD reported relevant symptoms of depression compared to 10.8% of the patients with NTNP (p = 1.00). About 16% of the patients with WAD and a comparable percentage of patients with NTNP reported symptoms of anxiety (p = .67). Finally, 14.3% of the WAD group reported symptoms of stress compared to 12.8% of the NTNP group (p = .16). Post-

4 M. S. STENNEBERG ET AL.

Page 7

Tabl

e 1.

Clin

ical

cha

ract

eris

tics

of p

atie

nts

with

WAD

, pat

ient

s w

ith N

TNP

and

pain

-fre

e in

divi

dual

s

Char

acte

rist

ics

Pain

-fre

e in

divi

dual

sW

AD

NTN

PD

iffer

ence

W

AD

vs

NTN

Pp*

Post

Hoc

Tota

l pat

ient

s (n

)33

616

833

6Ag

e (y

r) (m

ean

± S

D)

41.6

±13

.041

.3 ±

13.2

41.1

±13

.2Fe

mal

e (n

, %)

248

(73.

8)12

4 (7

3.8)

248

(73.

8)BM

I (m

ean

± S

D)

24.7

±4.

125

.4 ±

5.0

24.6

±3.

7Ed

ucat

ion

leve

l (n,

%)

Low

M

ediu

m

Hig

h

50 (1

4.9)

90

(26.

8)

196

(58.

3)

24 (1

4.3)

80

(47.

6)

64 (3

8.1)

53 (1

5.8)

13

7 (4

0.8)

14

6 (4

3.5)

Sym

ptom

dur

atio

n (w

ks) (

med

ian,

IQR)

14.0

(6.0

-52.

0)13

.0 (5

.0 –

50.

0)1.

0.3

8N

PRS

(0-1

0) (m

edia

n, IQ

R)6

(4-7

)5

(3-6

)1

<.0

1AC

ROM

(mea

n ±

SD

)Fl

exio

n- E

xten

sion

Rota

tion

(left+

right

)13

0.6°

±17

.3°

147.

0° ±

20.7

°10

6.5°

±26

.2°

123.

4° ±

26.3

°11

8.4°

±21

.3°

135.

8° ±

24.0

°11

.9°

(95%

CI 7

.6°-

16.2

°)

12.4

° (9

5%CI

7.8

°-17

.0°)

<.0

1 b

<.0

1 b

All p

<.0

1 Al

l p<

.01

NFE

T (s

ec.)

(med

ian,

IQR)

39.3

(27-

60)

25.0

(16-

38)

30.5

(21-

46)

5.5

<.0

1 b

All p

<.0

1N

DI (

0-50

) (m

edia

n, IQ

R)17

(12-

23)

10 (8

-14)

7<

.01

Activ

ity li

mita

tions

(0-4

) (m

edia

n, IQ

R)2

(1-2

)1

(0-2

)1

<.0

1Pa

rtic

ipat

ion

rest

r. (0

-4) (

med

ian,

IQR)

2 (1

-2)

0 (0

-1)

2<

.01

DAS

S-21

Dep

ress

ion

(n a , %

)N

orm

al (0

-9)

Mild

(10-

13)

Mod

erat

e (1

4-20

) Se

vere

(21-

27)

Extr

emel

y se

vere

(≥28

) M

ild a

nd a

bove

(≥10

)

125

(98.

4)

1 (0

.8)

1 (0

.8)

0 (0

.0)

0 (0

.0)

2 (1

.6)

67 (8

7.0)

3

(3.9

) 4

(5.2

) 1

(1.3

) 2

(2.6

) 10

(13.

0)

174

(89.

2)

9 (4

.6)

8 (4

.1)

1 (0

.5)

3 (1

.5)

21 (1

0.8)

2.2

<.0

1 b

WAD

vs

HC:

p=

.01

NP

vs H

C:

p=.0

1 W

AD v

s N

P: p

=1.

00

DAS

S-21

Anx

iety

(n a , %

)N

orm

al (0

-7)

Mild

(8-9

) M

oder

ate

(10-

14)

Seve

re (1

5-19

) Ex

trem

ely

seve

re (≥

20)

Mild

and

abo

ve (≥

8)

118

(92.

9)

4 (3

.1)

4 (3

.1)

0 (0

.0)

1 (0

.8)

9 (7

.1)

65 (8

4.4)

2

(2.6

) 7

(9.1

) 1

(1.3

) 2

(2.6

) 12

(15.

6)

163

(83.

6)

6 (3

.1)

15 (7

.7)

4 (2

.1)

7 (3

.6)

32 (1

6.4)

0.8

<.0

1 b

WAD

vs

HC:

p<

.01

NP

vs H

C:

p<.0

1 W

AD v

s N

P:

p=.6

7D

ASS-

21 S

tres

s (n

a , %)

Nor

mal

(0-1

4)

Mild

(15-

18)

Mod

erat

e (1

9-25

) Se

vere

(26-

33)

Extr

emel

y se

vere

(≥34

) M

ild a

nd a

bove

(≥15

)

125

(98.

4)

1 (0

.8)

1 (0

.8)

0 (0

.0)

0 (0

.0)

2 (1

.6)

66 (8

5.7)

5

(6.5

) 3

(3.9

) 1

(1.3

) 2

(2.6

) 11

(14.

3)

170

(87.

2)

14 (7

.2)

3 (1

.5)

5 (2

.6)

3 (1

.5)

25 (1

2.8)

1.5

<.0

1 b

WAD

vs

HC:

p<

.01

NP

vs H

C:

p<.0

1 W

AD v

s N

P:

p=.1

6D

istr

ibut

ion

of t

he n

eck

pain

Tota

l loc

atio

ns (m

edia

n, r

ange

)4

(1-7

)3

(1-7

)1

.02

Use

ana

lges

ics

for

neck

pai

n (n

, %)

<.0

1Ye

s N

o65

(38.

7)

103

(61.

3)63

(18.

8)

273

(81.

3)Co

mor

bid

low

bac

k pa

in (n

, %)

Com

orbi

d he

adac

he (n

, %)

43 (1

2.8)

83 (4

9.4)

11

2 (6

6.7)

134

(39.

9)

183

(54.

5)9.

5 12

.2.0

4 <

.01

bAl

l p<

.01

Mat

ched

gro

ups

for a

ge, s

ex a

nd d

urat

ion

of s

ympt

oms

(onl

y pa

tient

gro

ups)

. WAD

= W

hipl

ash

Asso

ciat

ed D

isor

ders

; NTN

P =

non

-tra

umat

ic n

eck

pain

; SD

= S

tand

ard

devi

atio

n; B

MI =

Bod

y M

ass

Inde

x; IQ

R =

Inte

rqua

rtile

ra

nge;

NPR

S =

Num

eric

al P

ain

Ratin

g Sc

ale;

ACR

OM

= A

ctiv

e Ce

rvic

al R

ange

of M

otio

n; N

FET

= n

eck

flexo

r mus

cle

endu

ranc

e te

st; N

DI =

Nec

k D

isab

ility

Inde

x; D

ASS-

21 =

sho

rt-f

orm

Dis

tres

s An

xiet

y St

ress

Sca

les;

*P

valu

e,

sign

ifica

nt a

t .0

5 le

vel;

a Th

e D

ASS-

21 w

as a

sses

sed

in t

he s

econ

d in

clus

ion

perio

d in

399

par

ticip

ants

, WAD

n=

77, N

TNP

n=19

5 an

d pa

in-f

ree

cont

rols

n=

127;

b O

vera

ll gr

oup

diffe

renc

es.

PHYSIOTHERAPY THEORY AND PRACTICE 5

Page 8

hoc analyses revealed that psychological factors were more prevalent in the patient groups than in the pain- free control group (p ≤ 0.01).

Patient-Specific Activity Limitations and Participation Restrictions

More patients with WAD indicated limitations in lifting and carrying objects (+23.9%), driving a car or motorcycle (+10.2%), and doing housework (+10.2%) compared to patients with NTNP. Patients with NTNP reported more problems in maintaining a sitting position (+8.0%), moving the head or cervi-cal spine (+6.8%), and caring for household objects and gardening (+5.7%) (Table 2).

Acute versus Chronic Symptoms

Patients with WAD had significantly higher pain intensity and disability compared to NTNP for both acute and chronic symptoms (p < .01). The WAD group also showed more than 11 degrees less range of motion in cervical flexion-extension and rotation than the NTNP group in both acute and chronic complaints (p < .01). For neck flexor muscle endur-ance, a statistically significant difference between the groups was found for chronic neck pain but not for acute neck pain. With respect to anxiety, depression and stress, no significant differences between the groups were observed (Table 3).

Discussion

This study shows that patients with WAD treated in primary care physiotherapy experience more pain, impairments, and disability as compared to patients with NTNP, but the levels of psychological factors are not higher. Pain-free controls had significantly better outcomes in physical and psychological functioning than the neck pain groups. More severe symptoms were observed in patients with both acute and chronic WAD compared to NTNP.

Patients with WAD reported slightly higher pain levels than patients with NTNP. This is in line with other studies reporting differences up to 1.7/10 points (Anstey, Kongsted, Kamper, and Hancock, 2016; Grip, Sundelin, Gerdle, and Karlsson, 2007). This difference, however, is small and can be interpreted as ‘noticeable but not meaningful’ (Cleland, Childs, and Whitman, 2008; Dworkin et al., 2008; Pool et al., 2007).

Regarding the bodily distribution of the neck pain, the WAD group reported more pain areas than patients with NTNP, confirming findings from previous studies

in which WAD patients presented larger pain areas (Hincapié et al., 2010; Ris et al, 2019). However, these studies are difficult to compare with ours because they determined total bodily pain, while we specifically mea-sured neck-related pain. In clinical practice, each addi-tional reported pain area seems to be important. Clinicians use this information to determine, for exam-ple, whether the pain radiates to the upper arm or fore-arm, which is then used for classifying neck pain and seems to be important for prognostics and clinical deci-sion-making (Blanpied et al., 2017; Childs, Fritz, Piva, and Whitman, 2004; Guzman et al., 2009).

Range of motion and muscle endurance were signifi-cantly less in the WAD group compared to the NTNP group. For muscle endurance, these differences only appeared in case of chronic neck pain. Observed differ-ences were clinically relevant and beyond the measure-ment error of the instruments used (Harris et al., 2005; Olson et al., 2006; Stenneberg et al., 2018). Other studies also consistently showed poorer results for the WAD group (Anstey, Kongsted, Kamper, and Hancock, 2016; Ris et al., 2017; Stenneberg et al., 2017). These differences suggest that identifying reduced cervical range of motion and muscle endurance should be considered in the clin-ical assessment and as possible treatment options depend-ing on what is deemed relevant for each individual patient.

Similarly, the consequences of neck pain on disability appear to be substantial for both groups, with the WAD group reporting greater disability than the NTNP. In our study, patients with WAD showed a 7-point higher disability score on the NDI than those with NTNP. This can be interpreted as a clinically important differ-ence in musculoskeletal neck pain (MacDermid et al., 2009; Vernon, 2000). Other studies are in line with these findings, reporting patients with WAD to have more self-reported disability than those with NTNP (Anstey, Kongsted, Kamper, and Hancock, 2016; Ris et al., 2017).

The prevalence and severity of anxiety, depression, and stress in our study was lower compared to other studies (Anstey, Kongsted, Kamper, and Hancock, 2016; Ris et al., 2017; Wiseman, Curtis, Lam, and Foster, 2015). This is likely because these studies were conducted in secondary care settings where patients with more severe symptoms and more psychological conditions can be expected (Anstey, Kongsted, Kamper, and Hancock, 2016; Wiseman, Curtis, Lam, and Foster, 2015). The finding of no difference between WAD and NTNP patients with respect to psychological outcomes is different to prior studies on this topic (Anstey, Kongsted, Kamper, and Hancock, 2016; Ris et al., 2017). One explanation could be that our sample showed relatively lower scores on

6 M. S. STENNEBERG ET AL.

Page 9

psychological factors, and reported less severe pain and disability than previous studies. Psychological factors show strong associations with chronic neck pain and severe pain and disability (Börsbo, Peolsson, and Gerdle, 2008; Dimitriadis, Kapreli, Strimpakos, and Oldham, 2015). Therefore, it seems to be important to assess psy-chological factors in primary care both in patients with WAD and those with NTNP.

Strengths and Limitations

This study used data that are likely to reflect the neck pain population in Dutch primary care physiotherapy; by including a pain-free group we could make mean-ingful clinical comparisons with neck patient groups. A potential limitation of this study was the participa-tion of different testers in multiple practices, which may have increased the variability of measurements and procedures but benefits the external validity. To decrease variability, a standardized protocol was used and all testers were well trained in the use of the measuring instruments and measurement procedures. Despite measurement errors and variability, several significant differences between patient groups were found, in particular in pain intensity, cervical range of motion, muscle endurance, and disability. Further, we have chosen to assess a pragmatic selection of physical functions and psychological factors, which are routi-nely performed in clinical practice to mimic daily care and adhere to guidelines. However, there may have been other factors that could also differentiate between WAD and NTNP, such as sensory hypoesthesia, pres-sure pain thresholds, dizziness, or cognitive perfor-mance such as memory and concentration symptoms or post-traumatic stress (Anstey, Kongsted, Kamper,

and Hancock, 2016; Chien and Sterling, 2010; Schmand et al., 1998). Therefore, differences in these factors not measured in this study might also be of clinical value. Yet, the factors included in our study are recommended by clinical guidelines in these patient groups and therewith form a representative set of mea-surements for primary care settings (Bier et al., 2018; Blanpied et al., 2017).

Clinical Implications

Patients with WAD and NTNP differ from pain-free individuals on various dimensions of the ICF. These differences are present from the acute phase onwards. This stresses the importance of assessing physical functions, such as cervical range of motion and mus-cle endurance, within clinical management, in addi-tion to disability and psychological factors, in both acute and chronic patients. Although uncertainty exists about the effectiveness of treating mobility and strength deficits in WAD, accurate and detailed diagnostics are of value and can be essential for the development and investigation of future interventions (Hancock et al., 2011).

Patients with WAD and patients with NTNP have their specific types of limitations in daily activities. In measuring these limitations, good content validity of the measurement instrument is essential. When we compare activity limitations and participation restric-tions that patients with neck pain consider important with the items in frequently used questionnaires, it appears that only a limited match is found. For example, the most commonly used and recom-mended NDI, includes only four from the top 15

Table 2. Top 15 most important activity limitations and participation restrictions to patients derived from the patient-specific functional scale.

WAD group Nontraumatic neck pain group

Activity limitation/ participation restriction (ICF-code) Frequency (%)

Activity limitation/ participation restriction (ICF-code) Frequency (%)

Lifting and carrying objects (d430) 45 (51.1) Maintaining a sitting position (d4153) 31 (35.2)Driving a car or motorcycle (d4751) 27 (30.7) Moving the head or cervical spine (d4108) 28 (31.8)Maintaining a sitting position (d4153) 24 (27.3) Lifting and carrying objects (d430) 24 (27.3)Doing housework (d640) 24 (27.3) Lying in bed (d4150) 22 (25.0)Moving the head or cervical spine (d4108) 22 (25.0) Using a computer (d4158) 22 (25.0)Lying in bed (d4150) 22 (25.0) Sports (d9201) 21 (23.9)Using a computer (d4158) 19 (21.6) Driving a car or motorcycle (d4751) 18 (20.5)Sports (d9201) 17 (19.3) Doing housework (d640) 15 (17.1)Reading (d166) 14 (15.9) Remunerative employment (d850) 13 (14.8)Remunerative employment (d850) 12 (13.6) Caring for household objects and gardening (d650) 11 (12.5)Bending over (d4105) 10 (11.3) Maintaining a standing position (d4154) 10 (11.3)Maintaining a standing position (d4154) 7 (8.0) Bending over (d4105) 8 (9.1)Reaching (d4452) 7 (8.0) Reading (d166) 7 (8.0)Walking and moving (d450) 7 (8.0) Reaching (d4452) 7 (8.0)Standing up or sitting down (d4100) 6 (6.8) Driving a bicycle (d4750) 6 (6.8)

The Patient Specific Functional Scale was only assessed in the first inclusion period: WAD group n = 88, Non-traumatic neck pain group n = 88; WAD = Whiplash Associated Disorders; ICF = International Classification of Functioning;

PHYSIOTHERAPY THEORY AND PRACTICE 7

Page 10

Tabl

e 3.

Clin

ical

cha

ract

eris

tics

betw

een

patie

nts

with

acu

te v

ersu

s ch

roni

c sy

mpt

oms

in p

atie

nts

with

WAD

and

pat

ient

s w

ith N

TNP

Char

acte

rist

ics

Acu

te W

AD

Acu

te N

TNP

Diff

eren

ce

WA

D v

s N

TNP

p*Ch

roni

c W

AD

Chro

nic

NTN

PD

iffer

ence

W

AD

vs

NTN

Pp*

Tota

l pat

ient

s (n

)72

148

9618

8Ag

e (y

r) (m

ean

±SD

)39

.7 ±

13.2

39.4

±13

.90.

342

.5 ±

13.1

42.4

±12

.5Fe

mal

e (n

, %)

56 (7

7.8)

114

(77.

0)0.

868

(70.

8)13

4 (7

1.3)

NPR

S (0

-10)

(med

ian,

IQR)

6.0

(3-7

)4.

0 (3

-6)

2<

0.01

6.0

(4-7

)5.

0 (3

-6)

1<

.01

ACRO

M (m

ean

±SD

)Fl

exio

n- E

xten

sion

Rota

tion

(left+

right

)11

1.0°

±25

.6°

127.

2° ±

29.4

°12

2.6°

±21

.1°

140.

1° ±

22.8

°11

.5 (9

5%CI

5.1

-18.

0)

12.8

(95%

CI 5

.7-1

9.9)

<0.

01

<0.

0110

3.1°

±26

.3°

120.

5° ±

23.5

°11

5.2°

±21

.0°

132.

5° ±

24.5

°12

.0 (9

5%CI

6.4

-17.

7)

12.0

(95%

CI 6

.0-1

7.9)

<.0

1 <

.01

NFE

T (s

ec.)

(med

ian,

IQR)

28 (1

9-50

)31

(18-

44)

30.

9122

(15-

35)

30 (2

2-47

)8

<.0

1N

DI (

0-50

) (m

edia

n, IQ

R)14

(10-

21.5

)10

(7-1

3)4

<0.

0119

(14-

24)

12 (8

-16)

7<

.01

Activ

ity li

m. (

0-4)

med

ian

(IQR)

2 (1

-2)

1 (0

-2)

1<

0.01

2 (1

-2)

1 (1

-2)

1<

.01

Part

icip

. res

tr. (

0-4)

med

ian

(IQR)

1 (0

-2)

0 (0

-1)

1<

0.01

2 (1

-3)

1 (0

-2)

1<

.01

DAS

S-21

Dep

ress

ion

(n a , %

)N

orm

al (0

-9)

Mild

(10-

13)

Mod

erat

e (1

4-20

) Se

vere

(21-

27)

Extr

emel

y se

vere

(≥28

) M

ild a

nd a

bove

(≥10

)

28 (9

3.3)

0

(0.0

) 1

(3.3

) 0

(0.0

) 1

(3.3

) 2

(6.7

)

100

(97.

1)

1 (1

.0)

2 (1

.9)

0 (0

.0)

0 (0

.0)

3 (2

.9)

3.8

0.33

39 (8

3.0)

3

(6.4

) 3

(6.4

) 1

(2.1

) 1

(2.1

) 8

(17.

0)

74 (8

0.4)

8

(8.7

) 6

(6.5

) 1

(1.1

) 3

(3.3

) 18

(19.

6)

2.6

.74

DAS

S-21

Anx

iety

(n a , %

)N

orm

al (0

-7)

Mild

(8-9

) M

oder

ate

(10-

14)

Seve

re (1

5-19

) Ex

trem

ely

seve

re (≥

20)

Mild

and

abo

ve (≥

8)

25 (8

3.3)

2

(6.7

) 2

(6.7

) 0

(0.0

) 1

(3.3

) 5

(16.

7)

92 (8

9.3)

4

(3.9

) 5

(4.9

) 1

(1.0

) 1

(1.0

) 11

(10.

7)

6.0

0.38

40 (8

5.1)

0

(0.0

) 5

(10.

6)

1 (2

.1)

1 (2

.1)

7 (1

4.9)

71 (7

7.2)

2

(2.2

) 10

(10.

9)

3 (3

.3)

6 (6

.5)

21 (2

2.8)

7.9

.26

DAS

S-21

Str

ess

(n a , %

)N

orm

al (0

-14)

M

ild (1

5-18

) M

oder

ate

(19-

25)

Seve

re (2

6-33

) Ex

trem

ely

seve

re (≥

34)

Mild

and

abo

ve (≥

15)

26 (8

6.7)

2

(6.7

) 0

(0.0

) 1

(3.3

) 1

(3.3

) 4

(13.

3)

96 (9

3.2)

5

(4.9

) 1

(1.0

) 1

(1.0

) 0

(0.0

) 7

(6.8

)

6.5

0.23

40 (8

5.1)

3

(6.4

) 3

(6.4

) 0

(0.0

) 1

(2.1

) 7

(14.

9)

74 (8

0.4)

9

(9.8

) 2

(2.2

) 4

(4.3

) 3

(3.3

) 18

(19.

6)

4.7

.49

WAD

= W

hipl

ash

Asso

ciat

ed D

isor

ders

; NTN

P =

non

-tra

umat

ic n

eck

pain

; SD

= S

tand

ard

devi

atio

n; IQ

R =

Inte

rqua

rtile

ran

ge; N

PRS

= N

umer

ical

Pai

n Ra

ting

Scal

e; A

CRO

M =

Act

ive

Cerv

ical

Ran

ge o

f Mot

ion;

NFE

T =

nec

k fle

xor m

uscl

e en

dura

nce

test

; ND

I = N

eck

Dis

abili

ty In

dex;

DAS

S-21

= s

hort

-for

m D

istr

ess

Anxi

ety

Stre

ss S

cale

s; *

p-va

lue,

sig

nific

ant a

t .05

leve

l; a

The

DAS

S-21

was

onl

y as

sess

ed in

the

seco

nd in

clus

ion

perio

d: A

cute

WAD

n=

30, A

cute

NTN

P n=

103,

chr

onic

WAD

n=

47, c

hron

ic N

TNP

n= 9

2

8 M. S. STENNEBERG ET AL.

Page 11

activities judged to be important according to patients. This corresponds to numbers found in pre-vious research (Hoving et al., 2003; Schmitt et al., 2013). The question is therefore, whether the NDI is suitable for measuring the ICF construct of activities and participation. Due to the specific limitations in activities we found, we recommend including assess-ments of patient-specific activity restrictions in the future research and clinical practice.

Much research has been conducted into psycholo-gical factors as predictors of the clinical course of neck pain. Only a few studies have assessed physical factors. The current study indicates that differences in factors, such as range of motion and strength, are also characteristic for subgroups of patients with neck pain. Research that includes a balanced set of biopsychosocial instruments may provide a better explanation for neck pain-related disability and the expected clinical course. It is assumed that different factors will be of varying importance in different individual patients. Furthermore, in research it is advisable to be aware of the differences between WAD and NTNP and, therefore, not to simply merge these groups when designing new diagnostic and therapeutic studies, or to combine these groups in meta-analyses.

In patients with neck pain, current guidelines recom-mend to improve functioning in daily life and reduce disability (Bier et al., 2018; Blanpied et al., 2017). This study illustrates that an important difference exists in the degree of disability between patients with WAD and patients with NTNP, which raises questions as to which factors can explain these disabilities. The extent to which patients function in daily life is complex and may depend on a variety of factors. Various biopsycho-social factors may have a different contribution to dis-ability. It is therefore recommended in future research to simultaneously investigate to what extent pain, impairments, and psychological factors contribute to disability, in order to understand the interactions between these factors and to improve the clinical man-agement of neck pain.

Conclusion

In WAD, there are more physical restrictions than in NTNP and should be considered as a separate sub-group of neck pain patients, in both acute and chronic symptoms. In order to distinguish between patients with WAD and NTNP in primary care prac-tices, it is recommended to assess at least pain inten-sity, cervical range of motion, cervical muscle endurance, and disability in addition to measuring

patient-specific activity limitations and participation restrictions. Levels of depression, anxiety, and stress do not seem to differ between these patient groups. We recommend taking differences between WAD and NTNP into account in the design of new studies and synthesis of results in systematic reviews and meta-analyses.

Acknowledgments

The authors would like to thank all physiotherapists and patients who participated in this study.

Disclosure statement

The authors report no funding sources or conflicts of interest.

ORCID

Martijn S. Stenneberg http://orcid.org/0000-0002-1969- 9152Gwendolyne G.M. Scholten-Peeters http://orcid.org/0000- 0002-4409-9554Emiel van Trijffel http://orcid.org/0000-0003-1192-7824Rob A. de Bie http://orcid.org/0000-0001-5882-9303

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