How Long Does a Systematic Review Take? A Realistic Timeline

The honest answer is: longer than most people planning one expect. A full systematic review, done properly, typically runs somewhere between four and twelve months from protocol to submission-ready manuscript.

Protocol development: 2 to 4 weeks

Before any searching begins, the question needs to be framed with PICO, eligibility criteria set, and the search strategy drafted and piloted. A rushed protocol creates rework at every later stage.

Systematic search: 1 to 3 weeks

Running the search across multiple databases, exporting results, and deduplicating records sounds mechanical, but a search across even three or four databases can return several thousand records before deduplication.

Screening: 4 to 10 weeks

This is usually the single longest stage. Title and abstract screening for a review with a broad topic can easily involve several thousand records, using two independent reviewers with a documented conflict-resolution method.

Data extraction and risk of bias: 3 to 6 weeks

For each included study, extracting outcome data accurately and assessing risk of bias with the correct tool takes meaningfully longer than it looks on paper, especially when double-extraction is used to catch errors.

Synthesis: 2 to 6 weeks

Meta-analysis, where the data supports it, requires model selection, heterogeneity assessment, and sensitivity analyses -- not just running a pooled estimate and reporting it.

Writing and PRISMA-compliant reporting: 3 to 6 weeks

Drafting the manuscript against the full PRISMA 2020 checklist, building the flow diagram so its numbers reconcile cleanly, and getting risk-of-bias and GRADE reporting into publication-ready shape takes longer than a first draft usually anticipates.

What actually moves the total time

Team size matters more than almost any other factor. Topic breadth matters just as much: a narrowly scoped clinical question moves far faster than a broad topic returning thousands of initial records.