Interpretation of the results of clinical trials involving medicines
Design hierarchy - and what each can and cannot answer
| Design | Answers | Cannot |
|---|---|---|
| RCT | Causation; randomisation balances known AND unknown confounders | Rare/late harms; external validity |
| Cohort | Incidence, prognosis, harm | Residual confounding |
| Case-control | Rare outcomes, efficient | Recall and selection bias; no incidence |
| Cross-sectional | Prevalence | Temporality |
| Meta-analysis | Precision, consistency | Cannot fix biased primary studies - "garbage in, garbage out" |
13 more sections, plus exam facts
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