Research and Evidence-Based Practice
What this domain tests
This domain tests whether you can find, appraise, and apply evidence: study designs, validity, statistical and clinical significance, and shared decision-making.
Core rules
- Form a PICO question: population, intervention, comparison, outcome.
- Evidence hierarchy: systematic reviews and meta-analyses of randomized trials sit above single randomized trials, cohort studies, case-control studies, cross-sectional studies, and expert opinion. A lower-level design can be appropriate when the question requires it.
- Internal validity asks whether bias was controlled; external validity asks whether results apply to your patient.
- Sensitivity and specificity describe test performance. A highly sensitive test is useful for ruling out when negative; a highly specific test is useful for ruling in when positive.
- Statistical significance (p-value) is not clinical importance. Look at effect size, confidence intervals, MCID, and number needed to treat.
Worked example
A screening test has 90% sensitivity and 50% specificity. A negative result is reassuring because few cases are missed, but a positive result is weak evidence because many people without the condition also test positive. Reasoning: high sensitivity supports ruling out; low specificity limits confirmation, so a positive result needs a more specific test or clinical evaluation.
Traps
Equating p < 0.05 with a clinically worthwhile effect. Assuming correlation proves causation. Using a highly sensitive test to confirm a diagnosis. Ignoring confidence intervals and study limitations.