Avoiding searching for outcomes called for additional search strategies: a study of Cochrane review searches

A search strategy for a systematic review that uses the Population, Intervention, Comparison, and Outcome framework should include the population, the intervention(s), and the type(s) of study design. According to existing guidelines, outcome should generally be excluded from the search strategy unless the search is multistranded. However, a recent study found that approximately 10% (51) of recent Cochrane reviews on interventions included outcomes in their literature search strategies. This study aims to analyze the alternatives to including outcomes in a search strategy by analyzing these recent Cochrane reviews.

This study analyzes the 51 Cochrane reviews that included outcomes in their literature search strategies and analyzes the results of alternative search strategies that follow current recommendations.

Despite a small study sample of 51 reviews the results show that many of the reviews excluded some of the recommended elements due to very broadly defined elements (e.g., all interventions or all people). Furthermore, excluding outcomes from the search strategy is followed by an enormous increase in the number of retrieved records making it unmanageable to screen, if using a single-stranded search strategy.

Recommendations for search strategies in difficult cases are called for.