Using the full PICO model as a search tool for systematic reviews resulted in lower recall for some PICO elements

• Published in: Journal of clinical epidemiology Vol. 127; pp. 69 - 75
• Main Authors: Frandsen, Tove Faber, Bruun Nielsen, Michael Friberg, Lindhardt, Christina Louise, Eriksen, Mette Brandt
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2020; Elsevier Limited
• Subjects: Childbirth & labor; Databases, Bibliographic; Embase; Epidemiology; Information Storage and Retrieval - methods; Keywords; Literature reviews; Pancreas; Pancreatic diseases; PICO; Pregnancy; PubMed; Retrieval; Reviews; Search methods; Search strategies; Search tools; Strategy; Subject heading schemes; Systematic review; Systematic reviews; Systematic Reviews as Topic - methods; Systematic searches; PICO; Embase; Systematic reviews; Systematic searches; Search tools; PubMed; Search strategies
• ISSN: 0895-4356; 1878-5921
• DOI: 10.1016/j.jclinepi.2020.07.005

The use of the four-part PICO model to facilitate search strategy development for a precise answer is recommended for structuring searches for systematic reviews. Existing guidelines generally recommend that a search strategy should include the population, intervention(s), and types of study design. Consequently, comparison and outcome are not recommended as a part of the search strategy. There is evidence that comparison and particularly outcome is not represented in enough detail, but this needs to be confirmed. The present study examines the presence of PICO elements in the records in two commonly used databases for health sciences research: Embase and PubMed. We examine the field of upper GI and pancreatic diseases as well as the field of pregnancy and childbirth by extracting the included studies as well as the related PICO elements from a random selection of Cochrane reviews within these two areas. We find that the PICO elements C and O had a lower retrieval potential across the two Cochrane groups and databases also when combining text words and subject headings. In particular, we find a lower retrieval when searching for both primary and secondary outcomes. Our results support the existing recommendation not to search for outcomes. •The PICO model is often used to develop the search strategy for a systematic review.•Existing guidelines generally recommend that a search strategy should include the population, intervention(s), and types of study design.•This study substantiates the assumption that when using PICO as a search strategy tool, some of the PICO elements will result in a considerably lower recall.•In particular, including outcomes as a search element will reduce recall as outcome is the element with the smallest retrieval potential of the four PICO elements and thus the results support the recommendation not to search for outcome.