Skip to Main Content

Evidence Based Practice

Appraising the Evidence

Don't Forget to Appraise the Evidence!

Appraising an article will generally involve asking 3 broad question:

Are the results of the study valid (Internal validity)?
What are the results?
Are the results applicable to your patient (External validity)?

CASP Case Control Study Checklist

RCT Appraisal Resources

RCT Appraisal Checklists

Calculate Results

How to calculate the number needed to treat (video)
Terry Shaneyfelt, MD, MPH (3 min)
The NNT Tutorial (video)
by Graham Walker (4 min)

Additional Resources

How to Critically Appraise a Therapy Study- Part 1 (video)
Terry Shaneyfelt, MD, MPH (9 min)
How to Critically Appraise a Therapy Study- Part 2 (video)
Terry Shaneyfelt, MD, MPH (10min)
Concealed Allocation: What Is It and Why Is It Important? (video)
Terry Shaneyfelt, MD, MPH (4 min)
Intention to treat analysis - What it is and why is it important (video)
Terry Shaneyfelt (5 min)
The “number needed to treat” turns 20 — and continues to be used and misused
McAlister FA. The "number needed to treat" turns 20--and continues to be used and misused. CMAJ. 2008;179(6):549–553. doi:10.1503/cmaj.080484
Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat
Alexandra Barratt, Peter C. Wyer, Rose Hatala, Thomas McGinn, Antonio L. Dans, Sheri Keitz, Virginia Moyer, Gordon Guyatt. CMAJ Aug 2004, 171 (4) 353-358; DOI: 10.1503/cmaj.1021197

Harm Appraisal Resources

Harm Appraisal Checklists

Calculate Results

How to calculate relative risk (video)
Terry Shaneyfelt, MD, MPH (3 min)
How to calculate an odds ratio (video)
Terry Shaneyfelt, MD, MPH (3 min)
How to Interpret and Use a Relative Risk and an Odds Ratio (video)
Terry Shaneyfelt, MD, MPH (11 min)

Additional Resources

How to Critically Appraise a Harm Study- Part 1 (video
Terry Shaneyfelt, MD, MPH (6 min)
How to Critically Appraise a Harm Study- Part 2 (video)
Terry Shaneyfelt, MD, MPH (7 min)
Tips for Teachers of Evidence-Based Medicine: Understanding Odds Ratios and Their Relationship to Risk Ratios
Prasad K, Jaeschke R, Wyer P, Keitz S, Guyatt G; J Gen Intern Med. 2008;23(5):635-640. doi:10.1007/s11606-007-0453-4

Diagnosis Appraisal Resources

Diagnosis Appraisal Checklists

Calculate Results

EBM 01: Intuitive Sensitivity & Specificity (video)
Rahul Patwari (9 min)
How to calculate sensitivity (video)
Terry Shaneyfelt (4 min)
How to calculate specificity (video)
Terry Shaneyfelt, MD, MPH (3 min)
What are likelihood ratios and how are they used (video)
Terry Shaneyfelt, MD, MPH (10 min)

Additional Resources

How to Critically Appraise a Diagnostic Test Study (video)
Terry Shaneyfelt, MD, MPH (13 min)
Diagnostic tests 4: likelihood ratios
Deeks Jonathan J, Altman Douglas G. Diagnostic tests 4: likelihood ratios BMJ 2004; 329 :168

Prognosis Appraisal Resources

Prognosis Appraisal Checklists

CEBM Critical Appraisal Sheet for Prognosis Studies

Interpret Results

Hazard Ratios and Survival Curves (video)
Rahul Patwari (11 min)
Interpreting Hazard Ratios (video)
Terry Shaneyfelt, MD, MPH (5 min)

Additional Resources

How to Critically Appraise a Prognosis Study (video)
Terry Shaneyfelt, MD, MPH (15 min)
Prognostic Study Designs (video)
Terry Shaneyfelt, MD, MPH (6 min)

Systematic Review Appraisal Resources

Systematic Review Appraisal Checklists

Interpret Results

How to Interpret a Forest Plot (video)
Terry Shaneyfelt, MD, MPH (5 min)
What is Heterogeneity? (video)
Terry Shaneyfelt, MD, MPH (9 min)

Additional Resources

How to Critically Appraise a Systematic Review: Part 1 (video)
Terry Shaneyfelt, MD, MPH (7 min)
How to Critically Appraise a Systematic Review: Part 2 (video)
Terry Shaneyfelt, MD, MPH (5 min)
PRISMA Statement, Explanation & Elaboration, Checklist, & Flow Diagram
The PRISMA 2020 statement comprises a 27-item checklist addressing the introduction, methods, results and discussion sections of a systematic review report.
PRISMA - Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)
Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) website!
Cochrane Handbook for Systematic Reviews of Interventions