Tips and tricks in performing a systematic review: Chapter 4 Building a PICO search strategy

Research output: Contribution to journalArticle (Academic Journal)peer-review

47 Citations (Scopus)


After identifying keywords that reflect your topic of interest, you need to use them to search for articles by building a ‘query’ more commonly known as a search string/strategy.

Successful search strategies are usually highly structured and built around a PICO framework. Population Intervention Comparison Outcome (PICO) frameworks help the searcher group search terms into thematic groups. PICO is very good at identifying medical literature where systematic reviewing is common, this is because the medical model of research can typically be defined by; a specific population for example, children; an intervention, for example, exercise regime; the type of comparison, for example, randomised control trial; and outcome, for example, weight control.

If you were to use the following headings and list all other synonyms relating to those headings for example, CHILDREN — paediatric, adolescent, etcetera; EXERCISE — physical activity, dance, sport, etcetera; RCT — randomise, comparison, etcetera; and WEIGHT CONTROL — fat, adiposity, BMI, etcetera, you would end up with four lists of terms. If you took one term from each group and then searched for all four terms in a query you would hopefully retrieve articles relating to an exercise intervention in children where one of the outcomes was weight loss.

The trick with a PICO framework is that it searches for all possible combinations of search terms, if you have five search terms in each group it searches 5!4 that is, 207 360 000 combinations. To link the search terms together logical Boolean operators are required. All search terms under one heading are linked by a Boolean OR, that is, this term or that term, and each group is linked by a Boolean AND, that is, this group of terms and that group of terms.

Fortunately, specific groups of search terms have been identified that locate specific types of literature. One such hedge was pioneered in Cochrane reviews and is used to locate randomised control trials; the Cochrane Highly Sensitive Search Strategy is well documented and widely used. Other groups of hedges exist and find articles that focus on therapy, diagnosis, review, prognosis, causation (aetiology), economics, cost, clinical prediction guides, and qualitative studies.

Next Chapter: Implementing a search and managing the results.
Original languageEnglish
Pages (from-to)136
Number of pages1
JournalBritish Journal of General Practice
Issue number547
Publication statusPublished - 1 Feb 2008


  • Biomedical Research
  • Humans
  • Review Literature as Topic


Dive into the research topics of 'Tips and tricks in performing a systematic review: Chapter 4 Building a PICO search strategy'. Together they form a unique fingerprint.

Cite this