Search Strategy Template & Worked Example

How to turn a PICO question into a documented, reproducible Boolean search string.

Step 1 — Break your PICO question into concepts

Example PICO question: "In adults with type 2 diabetes (P), does a low-carbohydrate diet (I), compared to a standard low-fat diet (C), reduce HbA1c levels (O)?"

Search concepts (usually just P and I — O and C are often left out of the search itself, then applied during screening, to avoid over-narrowing results):

Concept 1 (Population): type 2 diabetes
Concept 2 (Intervention): low-carbohydrate diet

Step 2 — List synonyms and related terms for each concept

Concept 1: Type 2 diabetes	Concept 2: Low-carbohydrate diet
"type 2 diabetes" "diabetes mellitus, type 2" "T2DM" "NIDDM"	"low-carbohydrate diet" "low carb diet" "ketogenic diet" "carbohydrate restriction"

Step 3 — Combine with Boolean operators

("type 2 diabetes" OR "diabetes mellitus, type 2" OR "T2DM" OR "NIDDM")
AND
("low-carbohydrate diet" OR "low carb diet" OR "ketogenic diet" OR "carbohydrate restriction")

Use OR within a concept (to capture any synonym), and AND between concepts (to require both).

Step 4 — Add database-specific tools

MeSH terms (PubMed) — add the controlled vocabulary term alongside free-text terms, e.g. "Diabetes Mellitus, Type 2"[Mesh].
Truncation — use a wildcard (e.g. diabet*) to capture variations like "diabetic," "diabetes."
Field limiters — restrict to title/abstract if a term is too broad as a full-text search.

Step 5 — Document everything

Record the exact search string, database, date range, and date the search was run for every database you search — this is what makes your search reproducible, and what PRISMA 2020 reporting requires.

Need a comprehensive multi-database search strategy built for your topic?

See Literature Search Strategy Support