Systematic review

A systematic review is a structured summary that gathers and appraises all the studies on a specific question. It sits near the top of the evidence hierarchy.

Definition from Shrinktionary, reviewed by Shariq Refai, MD, MBA, FAPA (last reviewed 2026-06-26). Shrinktionary is the network's language layer and carries the canonical short definition; this page adds the research-context detail below. Full definition on Shrinktionary →

A regular review is just an expert sharing an opinion about the research. A systematic review works differently. The authors decide in advance what question they're asking, where they'll search, and which studies count. Then they search, screen, and grade every study against those rules. The point is to remove cherry-picking, where a writer mentions only the studies that fit their view.

When you want to know what the evidence says about an anxiety treatment, a systematic review is usually a better starting point than any single study. Guideline groups such as the American Psychiatric Association and NICE lean heavily on them. The Cochrane Library is one well-known home for systematic reviews.

A systematic review of exposure therapy for specific phobias would search the medical databases, find every trial that tested it, and report what the whole body of evidence shows. That includes the weak studies, not only the strong ones.

A systematic review is only as good as the studies inside it. If the underlying trials are small or poorly run, the review should say so. Two reviews of the same topic can also reach different answers if they used different rules for which studies to include. Read the methods, not only the conclusion.