Step 3: Appraise
In this step you critically appraise the evidence for its validity, impact, and usefulness in clinical practice. If you do not use a systematic reviews database, you will have to appraise whether or not the research is clinically sound. There are many different types of research studies, including prognosis, diagnosis, harm/etiology, and therapy.
Suggested Readings:
- BMJ is an excellent resource that provides information on how to read a paper
- How to Read a Paper: The Basics of Evidence-based Medicine is available as an eBook
Hierarchy of Evidence
|
Adapted from: Melnyk, B. M. & Fineout-Overholt, E. (2005). Evidence-Based Practice in |
Systematic Reviews and Meta-Analysis |
| Randomized Control Trials | |
| Control Studies | |
| Case Controlled or Cohort Studies | |
| Qualitative Studies | |
| Single descriptive or qualitative study | |
| Expert committee opinions |
Clinical Question/Best Level of Evidence
Type of Clinical Question |
Suggested Level of Evidence |
|
Therapy |
RCT > cohort > case control > case series |
|
Diagnosis |
Prospective, blind comparison to a gold standard |
|
Etiology/Harm |
RCT > cohort > case control > case series |
|
Prognosis |
Cohort study > case control > case series |
|
Prevention |
RCT > cohort study > case control > case series |
|
Clinical Exam |
Prospective, blind comparison to gold standard |
|
Cost |
economic analysis |
Questions of therapy, etiology, and prevention, which can best be answered by a RCT, can also be answered by a meta-analysis or systematic review.
The hierarchy of evidence is often presented as a pyramid, ranking study types based on their research methods, with systematic reviews and meta-analyses at the top, and expert opinion and anecdotal experience at the bottom.