Step-by-step workflow
Translate the question into concepts
Separate the main concepts. For a PICO question, searches often use Population and Intervention/Exposure concepts; adding every outcome can make the search too narrow.
Collect synonyms and controlled vocabulary
List abbreviations, spelling variants, older terminology, brand/generic names and controlled vocabulary such as MeSH where supported.
Build concept blocks
Combine synonyms within a concept with OR; combine distinct concepts with AND. Use phrase searching, truncation and proximity operators only according to each database’s syntax.
Test against known relevant papers
Identify several papers that should be retrieved. If the strategy misses them, diagnose which concept/term caused the failure.
Choose sources appropriate to the question
Use multiple bibliographic databases for systematic reviews. Add trial registries, citation searching, grey literature and specialist databases when relevant.
Translate the search for each source
Do not paste PubMed syntax unchanged into another database. Map field tags, controlled vocabulary and operators.
Record exact strategies and dates
Save the full query exactly as run, platform/database, date, filters/limits and number retrieved. This is essential for reproducibility and PRISMA reporting.
Export results and deduplicate
Preserve raw exports before deduplication. Use a consistent reference manager/workflow and record the number removed.
Use backward and forward citation searching
Check references of key studies/reviews and papers that cite them. Document how and when citation searching was performed.
Update before submission
For long reviews, rerun the search near completion according to protocol so newly published evidence is not missed.
Free tools that do not require a paid API
- PubMed for biomedical literature searching.
- Google Scholar for supplementary citation discovery; it should not be the sole systematic-review database.
- Zotero for reference management and deduplication support.
- Spreadsheet/CSV screening for small projects, provided decisions and exclusions are recorded systematically.
Final checklist
- Concept blocks explicit.
- Synonyms and controlled vocabulary included.
- Known key papers retrieved.
- More than one appropriate source used for systematic reviews.
- Exact searches saved.
- Raw exports preserved.
- Deduplication documented.
- Search update plan defined.
Search documentation table
- For every database: database name, platform/provider, date searched, date coverage if relevant, complete search string, filters/limits and number retrieved.
- For supplementary searches: website/registry, exact query or browsing method, date, and number of records considered.
- For citation searching: seed article(s), forward/backward method, platform and date.
- For author/contact searches: who was contacted, what was requested and whether a response was received.
- For updates: record exactly what changed from the original search and how new records were integrated.
Common search failures
- Using only natural-language sentences instead of controlled vocabulary and synonyms.
- Applying language/date filters without scientific justification.
- Using too many AND concepts and accidentally excluding relevant records.
- Copying one database syntax into another without translation.
- Failing to search drug/device synonyms, previous names or acronyms.
- Deleting raw exports after deduplication, making the search impossible to audit.