How to Conduct a Systematic Review Step by Step

A systematic review answers a focused question by identifying, selecting, appraising and synthesising all relevant studies using a pre-specified, reproducible method. It takes months of work and ideally a team of at least two reviewers plus someone with search and statistical expertise.

The steps

1. Frame the question with PICO and decide the review type (effects, accuracy, prognosis).
2. Write a protocol with eligibility criteria, search plan, outcomes and analysis methods, and register it (see How to Register a Systematic Review on PROSPERO).
3. Search several databases and other sources with a reproducible strategy.
4. Remove duplicates and screen titles and abstracts, then full texts, with two independent reviewers and a record of exclusion reasons.
5. Extract data with a piloted form, in duplicate or with verification.
6. Assess risk of bias with a design-appropriate tool.
7. Synthesise: narrative synthesis, and meta-analysis if studies are sufficiently similar.
8. Assess certainty of evidence (for example with GRADE).
9. Report following PRISMA 2020, including a flow diagram and the full search strategy.
10. Update if the review will be used for decisions over time.

How long and how many people?

Time varies with the number of records and complexity; many reviews take a year or more. A team usually includes content experts, a methodologist or statistician and an information specialist or librarian.

Illustrative example

Invented for teaching. A team asks whether exercise reduces falls in older adults living in care homes. They register a protocol, search four databases, screen 3,200 records, include 18 trials, rate risk of bias, pool results in a random-effects meta-analysis and grade the certainty as moderate. The flow diagram reports each step.

Common pitfalls

• Starting without a protocol.
• A single reviewer screening and extracting.
• Changing outcomes after seeing the data without declaring it.

Key takeaways

• Pre-specify, search comprehensively, work in duplicate and report transparently.
• Use MRN's free PRISMA flow diagram generator and forest plot generator when presenting results.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.