ClinQuiry — Clinical Research, Taught in Sequence

Core summary

A systematic review uses a predefined, transparent protocol to identify, appraise, and synthesize all relevant studies on a focused question. It minimizes bias through comprehensive searching, explicit inclusion criteria, and quality assessment. PRISMA guides its reporting.

Detailed explanation

A systematic review follows a rigorous, step-by-step process: (1) Formulate a focused research question (often using PICO). (2) Register the protocol (e.g., on PROSPERO) to prevent selective reporting. (3) Search multiple databases comprehensively with a reproducible strategy. (4) Screen titles/abstracts, then full texts, against predefined inclusion/exclusion criteria — typically done independently by two reviewers. (5) Extract data systematically from included studies. (6) Assess risk of bias in each study (using tools like Cochrane RoB 2 for RCTs or Newcastle-Ottawa Scale for observational studies). (7) Synthesize findings — narratively, in tables, or quantitatively via meta-analysis if appropriate. (8) Assess certainty of evidence (e.g., using GRADE). (9) Report transparently following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), including the iconic flow diagram showing study identification, screening, eligibility, and inclusion. The Cochrane Collaboration has produced thousands of systematic reviews that inform clinical guidelines worldwide.

Clinical example

You want to know whether acupuncture reduces chronic low back pain. A systematic review would search PubMed, Embase, CENTRAL, and other databases, include all RCTs comparing acupuncture to sham/no treatment, assess each trial's risk of bias, and synthesize results — giving you the most reliable answer available.

Research example

The Cochrane Library contains over 8,000 systematic reviews covering interventions across all medical specialties. These reviews are regularly updated as new evidence emerges and serve as the foundation for clinical practice guidelines worldwide.

Knowledge check

Q1. What is the first step in conducting a systematic review?

Q2. What does the PRISMA flow diagram show?

Q3. Why do systematic reviews typically require two independent reviewers for screening?