Most teams need 6–18 months to complete a systematic review, with larger scopes and small teams pushing timelines past two years.
Writers and research leads ask this a lot because schedules, grants, and promotion clocks depend on it. The short answer: evidence syntheses take time. A formal review moves through protocol design, exhaustive searching, screening, appraisal, data work, and write-up. Each step has moving parts, approvals, and hand-offs. The pace hinges on scope, access to a skilled librarian, and the size and experience of the team.
Time Needed To Produce A Systematic Review: Typical Ranges
The figures below reflect common timelines reported by library services, Cochrane-style programs, and published audits. Use them as planning ranges, not fixed rules.
| Phase | Typical Time | Work Highlights |
|---|---|---|
| Protocol & Registration | 1–3 months | Refine question, draft protocol, register in PROSPERO, set criteria |
| Search Strategy & Runs | 1–3 months | Work with an information specialist, translate strategies across databases, manage grey literature |
| Screening (Titles/Abstracts) | 1–2 months | Dual screening, calibration, resolve conflicts, document reasons |
| Full-Text Screening | 1–2 months | Retrieve PDFs, dual decisions, log exclusions, update PRISMA flow |
| Data Extraction | 1–3 months | Pilot forms, duplicate extraction, contact authors when needed |
| Risk Of Bias & Synthesis | 1–3 months | Appraise studies, decide on meta-analysis or narrative synthesis |
| Manuscript & Peer Review | 2–4 months | Draft, revise, respond to peer review, final checks |
Several large datasets back these ranges. An analysis of registered projects reported a mean of about 67 weeks from start to publication, with teams of about five people on average. Library guides from major centers also warn that a full project often runs for a year or more. Rapid approaches can compress steps, but they still follow transparent methods and trade speed for breadth.
Why Timelines Stretch Or Shrink
Every project is different. These factors change the clock the most:
Scope And Complexity
Broad questions, many outcomes, or multiple comparators expand searching and screening loads. Niche topics with sparse evidence can also take time because retrieval turns into detective work, including grey sources and trial registries.
Team Size And Experience
A small team can finish, but parallel work speeds things up. Two independent reviewers for each step reduce rework. Access to an experienced information specialist often saves weeks by crafting and translating search strings correctly the first time.
Study Volume And Retrieval
High-yield searches produce big de-duplication files and long screening queues. Full-text retrieval across paywalls, interlibrary loan, and author contact adds days per study. Poor reporting in primary studies slows extraction and appraisal.
Methods Choices
Meta-analysis, subgroup plans, GRADE profiles, and sensitivity checks add steps. Living updates and registration changes add rounds of edits. Preprints and ongoing trials can lead to protocol amendments late in the process.
Standard Step-By-Step Timeline
Here is a practical view of the workflow. Your group may run tasks in parallel, yet the sequence remains the same.
1) Protocol And Registration
Convert a well-framed question into a protocol. Define eligibility, outcomes, comparators, and analysis plans. Decide on subgroups and sensitivity rules now to avoid post-hoc choices later. Register on PROSPERO when the scope involves health interventions.
2) Search Strategy Design
Partner with a librarian to build draft strategies for MEDLINE, Embase, CENTRAL, and subject databases. Translate terms, test recall, and agree on limits. Plan grey sources and trial registries. Keep a full search log for reporting against PRISMA-style checklists.
3) Search Runs And De-duplication
Export results, manage references in a tool like EndNote or Zotero, and de-duplicate carefully. Document database names, platforms, dates, and the exact strategy strings.
4) Title/Abstract Screening
Set up dual screening with a pilot round to calibrate decisions. Use blinded voting if your tool supports it. Track reasons for exclusion with a controlled list to speed full-text work.
5) Full-Text Screening
Pull missing PDFs through library services or contact authors. Log the reason for each exclusion at this stage; these entries populate the PRISMA flow and supplement.
6) Data Extraction
Design a pilot form, test on five studies, and refine fields. Run duplicate extraction for accuracy. Pre-specify how to handle multiple reports of one study, unit-of-analysis issues, and missing variance data.
7) Risk Of Bias
Use validated tools aligned with study design. Keep judgments independent with consensus resolution. Store justifications in the extraction sheet to save time later during write-up.
8) Synthesis And GRADE
Choose random- or fixed-effects models if a meta-analysis is appropriate. If pooling is not suitable, structure a clear narrative with tables that carry effect directions and certainty ratings. Prepare plain-language statements for the key outcomes.
9) Writing, Checks, And Submission
Draft methods with copy-and-paste-ready logs: searches, selection process, and appraisal rules. Build figures early so peer review changes are easier. Align the manuscript with the PRISMA 2020 statement before submission.
For reporting structure and minimum items, the PRISMA 2020 statement is the anchor. Cochrane handbooks, along with many academic libraries, echo similar steps and typical timeframes. Linking your report to that checklist speeds editor checks and reduces back-and-forth later in the process.
Planning Ranges Backed By Data
Two sources are frequently cited when teams set expectations. The first is a study that mined PROSPERO records and found a mean of about 67 weeks from project start to publication, with funded projects taking longer and teams averaging around five contributors (see BMJ Open 2017). The second is guidance from health-sciences libraries that budget a year or more for a full review, sometimes longer when the question or search footprint is wide.
These aren’t caps. Complex topics with many eligible trials or multiple subgroups can cross the two-year mark. Tight questions with a modest evidence base can land closer to six months, especially with an experienced crew and a librarian on board from day one.
Ways To Move Faster Without Cutting Corners
Speed gains come from process design, not shortcuts that raise bias. Use the menu below to shape your plan.
| Strategy | Possible Time Saved | Watch-Out |
|---|---|---|
| Involve A Librarian Early | 2–6 weeks | Schedule time for peer review of search strings |
| Run Steps In Parallel | 2–8 weeks | Keep clear ownership so decisions don’t drift |
| Use Screening Software | 1–4 weeks | Still run dual screening; log reasons cleanly |
| Prebuild Extraction Forms | 1–3 weeks | Pilot on a small set before scaling |
| Limit To Core Outcomes | 1–3 weeks | State choices in the protocol to avoid bias |
| Template Figures & Text | 1–2 weeks | Map templates to PRISMA 2020 items |
Sample Year-Long Plan You Can Adapt
Here’s a simple outline you can tweak:
Months 1–2
Lock the question, write the protocol, register, and book time with a librarian. Draft database lists and test a search or two.
Months 3–4
Finalize search strings, run all databases and registries, export results, and de-duplicate. Set up screening software and train the team.
Months 5–6
Run title/abstract screening with two reviewers. Start retrieving full texts in parallel.
Months 7–8
Complete full-text decisions. Build and pilot extraction forms. Assign studies to pairs.
Months 9–10
Finish extraction and risk-of-bias judgments. Start synthesis and draft results tables.
Months 11–12
Write methods and discussion, complete figures, check against the PRISMA checklist, and submit.
When A Rapid Review Fits The Need
Stakeholders sometimes need an answer on a shorter schedule. Rapid formats streamline searches, narrow outcomes, or use single-reviewer screening with verification. Published methods papers describe windows from one to twelve months, with trade-offs clearly described in the report. Use them when a quick, transparent map of the evidence is more useful than exhaustive breadth.
Practical Tips That Save Weeks
Set Decision Rules Up Front
Create a short manual with examples of includes and excludes. Calibrate early so later rounds move smoothly.
Name One Person For Each Step
Give clear ownership for searches, screening, extraction, appraisal, and synthesis. Shared ownership slows decisions.
Track Everything
Keep a change log, search log, and screening log. These feed the write-up and make peer review faster.
Tame Reference Chaos
Set file-naming rules and folder structure on day one. Use consistent tags to mark stage and decision for each record.
Protect Quiet Time
Blocking time for screening and extraction beats drips of work. Short, focused sprints keep momentum.
Budget For Quality Checks
Plan small audits at each stage. Catching drift early costs less than re-doing a month of screening.
Typical Team Makeup And Roles
Most successful projects include two content experts, one method lead, one librarian, and at least two independent reviewers. Pairs handle each decision stage so no single opinion carries the day. The librarian designs and peer-reviews searches, the method lead steers protocol decisions and synthesis choices, and content experts interpret nuances in outcomes and comparators. A statistician joins when pooling is likely or when cluster trials and crossover designs appear. Assign a project manager, even if part-time, to track deadlines, meeting notes, and logs.
This mix keeps work moving in parallel while preserving checks and balances. With fewer people, protect independence by rotating roles across stages. With a larger group, guard against drift by naming a single owner for each step and keeping a tight change log.
Bottom Line For Planning
If you need a single line for a grant or a departmental plan, budget a year. Build slack for scope changes and peer review. Add time for meta-analysis, GRADE profiles, or broad questions. If the deadline is tight, choose a rapid format and report the streamlining choices clearly.
Helpful references: the PRISMA 2020 statement and Cochrane guidance on methods and timelines. Both map neatly onto the steps above and give checklists you can follow during planning and write-up.