การปฏิบัติตามหลักฐานเชิงประจักษ์ (Evidence-Based Practice: EBP) 2551
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1. (Introduction) 4 2. (Asking answerable question) 5 3. (Acquiring the evidence) 7 4. (Appraising the evidence) 13
(Etiology / Harm) 13 (Prognosis) 14 (Diagnosis) 15
/ (Therapy / Prevention) 16 (Systematic reviews) 17 (Economic analysis) 18 5. (Applying the evidence) 19 6. (Assessing outcome) 21 7. (Glossary) 23
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(EBM) EBM = (Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients, David L Sackett) EBM (information explosion) EBM (Etiology/Harm) (Diagnosis) (Prognosis) / (Therapy/Prevention) (Health economics) EBM (The 5 As of EBM) 1. A sk question : 2. A cquire evidence : 3. A ppraise evidence : 4. A pply evidence : 5. A ssess outcome :
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EBM (Asking clinical question) P I C O
1. (P roblem or P atient) 2. (I ntervention) 3. (C omparison intervention) 4. (O utcome)
(P)
.....
(I)
........................ estrogen .......
(C)
............... estrogen ........................................
(O)
.....
(Etiology/Harm) (Prognosis) (Diagnostic test) (Therapy or prevention) (Health economics)
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PICO (asking clinical question)
Domain Patient (P) Intervention (I) Comparison (C)
Outcome (O)
Therapy
acute
M.I.
aspirin
placebo
recurrent M.I.
Prognosis
hemodialysis
hemodialysis
.
life expectancy
Diagnosis
coronary disease
exercise ECHO
exercise EKG
coronary artery disease
Etiology / Harm
hormone
replacement therapy (HRT)
HRT
CA breast
Economic
chronic renal
failure
renal
transplant
hemodialysis
(cost- effective)
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EBM (Acquiring evidence) 1. (key words) (P) (I) (C) (O) domain (etiology, diagnosis, prognosis therapy, prevention, etc.) (cohort studies, case-control studies, randomized controlled trial, systematic review, meta-analysis) 2.
Cochrane Library http://gateway.ovid.co
m website
Bibliographic database (MEDLINE)
www.pubmed.com
CATs (Critically appraised topics)
www.ebem.org/cats/
appraise
appraise
TRIP (Turning Research Into Practice)
www.tripdatabase.com
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3. internet websites
PUBMED OVID MEDLINE 1. PUBMED National Library of Medicine
www.pubmed.com address web browser (Internet Explorer) 1
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Click Clinical Queries ( 1) 2
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category ( 2) therapy diagnosis etiology prognosis Enter subject search click Go
2. OVID MEDLINE : PUBMED OVID MEDLINE OVID server . (http://library.ra.mahidol.ac.th) OVID 3
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14 1 click
select more than one database to search 5
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click click to begin search 4
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(Medical subject Heading, MeSH) Enter Keyword or
phrase check box Limit to click PICO prognosis cohort studies, prognosis, survival analysis
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Ovid Medline Filters for Evidence-based Clinical Queries
Enter Keyword or phrase click
Domain : Therapeutics/Interventions Domain : Diagnosis1 exp research design/ 2 exp clinical trials/ 3 comparative study/ or placebos/ 4 multicenter study.pt. 5 clinical trial$1.pt. 6 random$.ti,ab. 7 (double blind$ or triple blind$3).ti,ab. 8 placebo$.ti,ab. 9 (clinical adj trial$1).ti,ab. 10 exp epidemiologic research design/ 11 (controlled clinical trial or randomized controlled trial).pt. 12 practice guideline.pt. 13 feasibility studies/ 14 clinical protocols/ 15 exp treatment outcome/ 16 or/1-15
1 exp "sensitivity and specificity"/ 2 false negative reactions/ or false positive reactions/ 3 (sensitivity or specificity).ti,ab. 4 (predictive adj value$1).ti,ab. 5 (likelihood adj ratio$1).ti,ab. 6 (false adj (negative$1 or positive$1)).ti,ab. 7 (randomized controlled trial or controlled clinical trial).pt. 8 double blind method/ or single blind method/ 9 practice guideline.pt. 10 consensus development conference$.pt. 11 random$.ti,ab. 12 random allocation/ 13 (single blind$3 or double blind$3 or triple blind$3).ti,ab. 14 or/1-13
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Domain : Etiology Domain : Prognosis 1 random$.ti,ab. 2 exp epidemiologic studies/ 3 odds ratio/ 4 cohort$.ti,ab. 5 (case$1 adj control$).ti,ab. 6 risk$.ti,ab. 7 (odds adj ratio$1).ti,ab. 8 causa$.ti,ab. 9 (relative$1 adj risk$).ti,ab. 10 predispos$.ti,ab. 11 (randomized controlled trial or controlled clinical trial).pt. 12 exp risk/ 13 practice guideline.pt. 14 case-control studies/ 15 or/1-14
1 exp cohort studies/ 2 prognosis/ 3 exp mortality/ 4 exp morbidity/ 5 (natural adj history).ti,ab. 6 prognos$.ti,ab. 7 course.ti,ab. 8 predict$.ti,ab. 9 exp "outcome assessment (health care)"/ 10 outcomes$1.ti,ab. 11 (inception adj cohort$1).ti,ab. 12 disease progression/ 13 exp survival analysis/ 14 or/1-13
key word Enter Keyword or phrase click
16+17 search strategy save option save username password ()
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(Etiology) (Harm) 1. (valid)
1.1 1.2 1.3 2 1.4 80
1.5
2. (importance) relative risk (R.R.) cohort study odds ratio (O.R.) case-control study (confidence interval or C.I.) 1 () NNH (number needed to harm) 1
NNH = [{PEER (OR 1) } +1] / [PEER (OR 1) x (1 PEER)] [PEER = patients expected event rate ]
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(Prognosis) 1. (valid)
1.1
1.2
1.3 (adjust)
1.4
1.5 80 1.6 blind
2. (importance)
2.1. (risk of outcome) 3
- - 50 - 2.2 (precision)
(confidence interval)
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(Diagnosis) 1. (valid)
1.1 (gold or reference standard) 1.2 1.1 blind (/
) 1.3 1.4 (reproducible)
2. (importance) accuracy test 2.1 sensitivity :
2.2 specificity : 2.3 predictive values : 2.4 likelihood ratio (L.R) :
Disease present (gold std) Disease absent (gold std) Test + a b Test - c d Sensitivity = a/(a+c) Specificity = d/(b+d) Positive predictive value = a/(a+b) Negative predictive value = c/(c+d) L.R. for positive test = {a/(a+c)}/{b/(b+d)} L.R. for negative test = {c/(a+c)}/{d/(b+d)} Prevalence (or pre-test probability) = (a+c) / (a+b+c+d)
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/(Therapy/Prevention) 1. (valid)
1.1 1.2 1.3 (randomized list concealed) 1.4 80 1.5 intention-to-treat (analyze as randomized) 1.6 1.7
2. (importance) 2.1 p-value (
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(Systematic reviews) 1. (valid)
1.1 1.2 1.3 (validity) 1.4
2. (importance)
2.1 2.2 2.3 (precision) confidence interval
2.4 3. (Applicability) 3.1 3.2 3.3 3.4
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(Economic analysis) 1. (valid)
1.1 2 1.2 cost-effectiveness, cost-benefit cost-utility 1.3 cost outcome 1.4 sensitivity analysis
2. (importance)
2.1 cost outcome 2.2 cost outcome (subgroup) 2.3 (sensitivity analysis)
3. (Applicability) 3.1 3.2 3.3
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6. 6.
Diagnostic test pre-test probability
Pre-test odds = (pre-test probability) / (1 pre-test probability) Post-test odds = pre-test odds x LR Post-test probability = post-test odds (ost-test odds + 1) Therapy PEER (Patients Expected Event Rate) NNT () = 1 / (PEER x RRR) 3. 4. 5. 6.
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- - - outcome -
David Sacket. Evidence-Based Medicine : How to Practice and Teach EBM ( New York : Churchill Livingstone, 2000) www.cebm.net www.cebm.utoronto.cawww.cochrane.org
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Glossary of Evidence-based Medicine
Absolute risk reduction (ARR) treatment effects Accuracy (true positive + true negative) / (true positive + true negative + false positive + false negative) Age standardization () Alpha error error Type I Alternative hypothesis hypothesis Analytic study cross-sectional, cohort case-control Anectdotal evidence 1 (case report) Association 2 (statistical association) (causal association) Attributable fraction (exposed, A.R.) exposure (IE - IU ) / IU (RR - 1) / RR IE incidence in the exposed group, IU incidence in the unexposed group, RR = relative risk Attributable fraction (population, P.A.R.) () exposure (IT - IU ) / IU B(RR - 1) / {B(RR-1) + 1} IT incidence in the total population, IU incidence in the unexposed group, RR = relative risk, B = (exposed proportion)
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Attributable risk (exposure, E) IE - IU excess risk Beta error error Type II Bias (systematic error) (non-systematic or random error) Blinding single-blind double-blind intervention Case-control study (case) (control) (exposure) odds ratio Case series () () Cause ( Hills criteria) -temporality : -strength : -experiment : -consistency : 1 -coherence : -specificity : -dose-response relationship -biologic plausibility : Chi-square test (discrete or categorical variables)
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Clinical decision analysis intervention 3 (choice) (chance) (values) intervention Clinical epidemiology classical epidemiology Clinical practice guideline (CPG) Clinical significance magnitude of effect Clinical trial interventions interventions Cluster sampling Cohort Cohort study 2 (exposure) 2 Co-intervention intervention intervention Confidence interval (CI) 95 95% CI = 5 - 15 90 99 Confidence limits (CL) confidence interval
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Confounding 2 3 Confounding variable, confounder ( 3) 2 Contamination control intervention Control group, controls Control event rate (CER) event rate Correlation coefficient 2 continuous 1 +1 1 1 (linear relationship) Correlation (ecological) study Cost-benefit analysis () Cost-effectiveness analysis () () intervention Cost-minimization analysis () (health effect) Cost-utility analysis (utility) quality gain quality-adjusted life year (QALY) 1 Critical appraisal (validity) (application)
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Crossover study design 2 Cross-sectional study (exposure) (outcome) Cumulative incidence average risk Decision analysis (or clinical decision analysis) Deduction Descriptive epidemiology Differential misclassification misclassification Dose-response relationship outcome exposure Double-blind blinding Dropout Ecological fallacy Ecological survey (aggregated data) (risk factor) (outcome) Effectiveness efficacy Efficacy effectiveness Efficiency
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Error, type 1 (alpha error) null hypothesis Error, type 2 (beta error) null hypothesis Event rate EER (experimental event rate) CER (control event rate) PEER (patient expected event rate) treatment effects Evidence-based health care (evidence-based medicine) Evidence-based medicine Experimental event rate (EER) event rate Exposure External validity validity False negative False positive Gold standard Hawthorne effect Hierarchy of evidence I: randomized controlled trial 1 study II-1 controlled trial randomization
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II-2 cohort case-control studies 1 II-3 uncontrolled studies III (case report / series) Historical control () Hypothesis -null hypothesis (H0) -alternative hypothesis (HA) Inception cohort () Indirect standardizeation/adjustment standardization Inference inferential statistic Information bias exposure outcome Informed consent Intention-to-treat analysis Internal validity validity Kappa 2 2 (P0 Pc) / (1 Pc) P0 = observed agreement, Pc = chance agreement Lead-time bias ()
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Length bias ( ) Likelihood ratio (LR) Positive LR = Sensitivity / (1 Specificity) Negative LR = (1 Sensitiivity ) / Specificity Meta-analysis Misclassifaction
-differential misclassification -non-differential misclassification Negative predictive value (NPV) Null hypothesis hypothesis Number needed to treat (NNT) 1 1 / ARR Observational study intervention Odds p / (1 - p) Odds ratio 2 odds odds of case ( exposure exposure ) odds of control ( exposure exposure )
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Outbreak epidemic p-vale (probability value) null hypothesis Patient expected event rate (PEER) event rate Power () 1- beta error Type II Positive predictive value (PPV) Post-test odds pre-test odds x likelihood ratio Post-test probability post-test odds / 1 + post-test odds Precision (reliability, repeatability, reproducibility) (valid) Pre-test odds pre-test probability / (1 + pretest probability) Pre-test probability or prevalence (point prevalence) (period prevalence) Publication bias Random error Randomization (or random allocation) () outcome
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Randomized controlled clinical trial (RCT) randomize Recall bias Relative risk reduction (RRR) treatment effects Research Risk Risk ratio (RR) () () RR = EER / CER Screening Sensitivity a / a + c SnNout sensitivity (Sn) (N) rule out Specificity d / b + d SpPin specificity (Sp) (P) rule in Standardization 2 -direct standardization -indirect standardization Statistical significance p-value 0.05 Survival analysis Systematic error bias Systematic review (critical appraisal)
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Treatment effects ARR (absolute risk reduction) = EER - CER RRR (relative risk reduction) = (EER - CER) / CER good outcome RRI (relative risk increase) = (EER - CER) / CER bad outcome ABI (absolute benefit increase) = ARR RBI (relative benefit increase) = RRR NNT (number needed to treat) = 1 / ARR good outcome NNH (number needed to harm) = 1 / ARR bad outcome EER = experimental event rate; CER = control event rate Validity ( bias) Validity, study -internal validity -external validity (generalizability)
(EBM) 2
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1 2Domain : Etiology(Etiology) NNH = [{PEER (OR 1) } +1] / [PEER (OR 1) x (1 PEER)](Prognosis) (Diagnosis)a
/(Therapy/PrevenARR=CEREER; RRR=(CER EER) / CER
(Systematic re (Economic ana
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