A systematic review usually takes 6–12 months end to end; rapid reviews run 2–12 weeks, while complex reviews can extend to 12–24 months.
Planning a systematic review means planning your calendar. Timelines stretch or shrink based on scope, team size, search volume, and how much synthesis you need. The steps are predictable, though: frame a question, register a protocol, search widely, screen records, extract data, appraise study quality, synthesize findings, and write. Add peer review, and you have the full arc. This guide lays out time ranges that real teams use, shows where delays hide, and offers ways to keep momentum without cutting standards.
How Long A Systematic Review Takes: By Stage
The table below maps each stage to common tasks and a realistic time range. Ranges assume a focused clinical or public health question, a trained librarian or search expert, two independent screeners, and standard software for screening and extraction. Solo projects or sprawling topics land on the longer end.
| Stage | What Happens | Typical Time |
|---|---|---|
| Question & Scope | Refine PICO, draft inclusion rules, set outcomes and subgroups | 1–3 weeks |
| Protocol | Write methods, plan search, set screening and analysis rules | 2–4 weeks |
| Registration | Register protocol and respond to minor clarifications | 1–2 weeks |
| Search | Design strings, run databases, grey literature, deduplicate | 2–6 weeks |
| Screening | Title/abstract and full-text decisions with dual review | 3–8 weeks |
| Data Extraction | Pilot forms, extract outcomes, contact authors if needed | 3–6 weeks |
| Risk Of Bias | Apply tools (e.g., RoB 2, ROBINS-I) with consensus | 2–5 weeks |
| Synthesis | Narrative summary; meta-analysis where fit; sensitivity runs | 2–6 weeks |
| Write-Up | Draft report, figures, flow diagram, tables, appendices | 3–6 weeks |
| Submission & Peer Review | Submit, revise, resubmit; timing varies by journal | 8–20 weeks |
What Drives The Timeline
Several levers add days or shave them. Tight, answerable questions move faster than open topics. A librarian cuts search time and improves recall. Dual screeners speed decisions and cut errors. A focused outcome set trims extraction time. Heterogeneous measures or mixed designs add effort during synthesis. Stakeholders who need subgroup answers or equity slices add layers. Living updates need steady bandwidth. Clear file naming, version control, and meeting rhythms keep drift in check.
Scope And Eligibility
Broad scope pulls in thousands of records, which slows screening and full-text retrieval. Narrow scope speeds things up but can miss useful signals. A crisp population, setting, comparator, and outcome list brings balance. Predefine time limits only when they serve the question, not to save time, or you risk bias. Pretesting inclusion rules on a small batch aligns the team and avoids rework.
Search Volume And Access
Multiple databases and grey sources boost coverage. They also create duplicates and diverse formats. Good deduplication pays off. Access barriers slow full-text retrieval; library services or interlibrary loan help. When contact with authors is needed, build slack time for replies and follow-ups.
Data Complexity
Simple outcomes and shared measures allow quick pooling. Diverse scales, cluster designs, or time-to-event data add conversions and assumptions. Harms, rare events, or network comparisons add layers. Plan sensitivity checks early so they do not become a scramble near submission.
Systematic, Scoping, And Rapid Reviews: Time At A Glance
A full systematic review aims for exhaustive, reproducible methods with dual decisions and full appraisal. A scoping review maps concepts, sources, and gaps, often without risk-of-bias ratings or meta-analysis. A rapid review streamlines steps to deliver answers faster, such as single screening with verification or narrower sources. For methods standards, the Cochrane Handbook lays out core processes; when speed is the driver, Cochrane’s updated rapid review guidance explains trade-offs and safeguards.
Time ranges differ by type. A typical scoping review lands near 3–9 months, depending on how much charting and stakeholder input you need. A rapid review can land in 2–12 weeks when scope is tight and methods are pre-templatized. Full systematic reviews often need 6–12 months, and large or mixed-method topics can push past a year.
Realistic Schedules You Can Plan Around
Use these scenarios to match your context. Each row assumes a focused question and access to core databases, with software for screening and extraction. Timelines reflect steady work with clear roles and regular check-ins.
| Scenario | Team & Scope | Likely Duration |
|---|---|---|
| Graduate Thesis | Solo lead, advisor checks; modest scope; part-time effort | 9–18 months |
| Small Lab Team | PI, librarian, 2 screeners; focused outcomes; meta-analysis likely | 6–12 months |
| Program-Funded Review | Project manager, librarian, 3–4 screeners, statistician | 4–9 months |
| Rapid Review | Tight question; streamlined steps; brief narrative synthesis | 2–12 weeks |
| Scoping Review | Broad mapping; charting only; no pooling | 3–9 months |
| Living Review | Core build plus periodic updates; automation where fit | Build: 3–6 months; updates monthly or quarterly |
Week-By-Week For A Six-Month Plan
Weeks 1–2: Nail The Question
Lock the population, intervention or exposure, comparator, and outcomes. Draft inclusion rules with clear edges. Set one channel for day-to-day decisions. Create a shared folder with templates for PRISMA flow, screening forms, and data fields.
Weeks 3–4: Protocol And Registration
Write methods, plan subgroup and sensitivity tests, and map databases. Pretest screening rules on a small set. Register the protocol. Decide on software for screening, extraction, and bias ratings. Assign roles and define tie-breaker steps.
Weeks 5–8: Search And Deduplicate
Run strings in major databases and subject portals. Export, clean, and deduplicate. Capture search dates and strategies for reporting. If grey sources matter, schedule time for targeted site searches and reference checks.
Weeks 9–14: Screen Titles, Abstracts, And Full Texts
Two reviewers screen in parallel with conflict resolution daily. Track reasons for exclusion at full text. Log contact attempts for missing data. Keep a pacing target per day so the pool does not balloon.
Weeks 15–18: Extract And Judge Bias
Pilot extraction on five studies and adjust fields. Extract outcomes, comparators, and key design details. Apply bias tools suited to your designs. Record justifications, not only labels, to make synthesis smoother.
Weeks 19–22: Synthesis And Figures
Start with a structured narrative. Add meta-analysis when designs and measures align. Build forest plots and tables. Run sensitivity checks that match protocol plans. Draft plain-language statements for each outcome.
Weeks 23–26: Write, Check, And Submit
Assemble main text, tables, appendices, and the flow diagram. Check reproducibility: search strings, dates, and decisions should be traceable. Select a journal that fits the scope and methods. Submit and prepare for a round of revisions.
Ways To Save Time Without Cutting Standards
Pair A Librarian With The Team
Search experts lift recall and trim trial-and-error. They also speed deduplication and documentation. One day of expert time can save weeks across the project.
Prebuild Templates
Ready-made screening forms, bias checklists, and extraction sheets shorten setup. Use short, unambiguous labels and fixed lists where fit. Pilot on a small batch to catch edge cases.
Screen In Parallel
Two reviewers working in parallel speed decisions and cut rework later. A third reviewer settles conflicts fast. Clear daily quotas keep the funnel moving.
Automate Repeatable Steps
Use deduplication features, reference managers, and screening tools that learn from decisions. Automation does not replace human checks, but it reduces clicks and keeps fatigue down.
Write As You Go
Maintain a living methods section and table shells from day one. Drop in search dates, counts, and decisions as they happen. By synthesis week, the report is half built.
Common Bottlenecks And Fixes
Scope Creep
New subquestions sneak in, and the record pool doubles. Fix this with a brief change log and a rule that the team approves any scope change. If a new angle matters, schedule it as a follow-on review.
Full-Text Chasing
Paywalls and missing PDFs stall progress. Set a standard window for retrieval and use library services early. Record which studies remain unavailable and note the impact on risk of bias and certainty ratings.
Data That Will Not Line Up
Outcomes appear on different scales or at different time points. Create a hierarchy of preferred measures before extraction. If pooling stays out of reach, keep the narrative clear and structured.
Slow Consensus
Endless back-and-forth drains time. Use short daily huddles for conflicts, with one decider on call. Log decisions to keep rulings consistent across screeners.
Reporting That Meets Editorial Standards
Editors and readers expect clean reporting of what you did and why. Follow a reporting checklist and include a flow diagram, full search strategies, and a clear summary of findings. Methods and results should match the protocol, and any change should be flagged with a short reason. The aim is clarity and reproducibility, not volume. When your review falls in health or public health, align with the methods in the Cochrane Handbook. When speed is required, apply safeguards from recognized rapid review guidance so readers can judge trade-offs.
Submission And Peer Review Time
Journal pathways vary. Some titles send first decisions in six to eight weeks; others take longer. A clean methods section, transparent tables, and data files shorten the revision cycle. Expect at least one round of changes, often two. Build a month or two for revisions into your plan, and keep your screening and extraction notes handy so you can answer queries fast.
What To Expect
A well-run systematic review with a focused question and a small, trained team often lands between six and twelve months. Shorter paths come from tight scope, strong search help, parallel screening, and clear forms. Longer paths come from broad topics, missing data, complex designs, and heavy subgroup work. With a plan that fits your setting, reliable documentation, and steady check-ins, the timeline becomes manageable and the output stays credible.