Gynecological trials frequently exclude people based on their symptoms rather than their condition: a systematic review of Cochrane reviews and their component trials

Abstract

Objectives: To identify strategies used in recent randomized controlled trials (RCTs) and their associated Cochrane Reviews where patients with the same gynecological condition present with different symptoms but would plausibly benefit from a common intervention.

Study design and setting: We searched the Cochrane library (February 2022) for reviews in polycystic ovarian syndrome (PCOS) and endometriosis. Reviews were included if the intervention was intended to treat all condition-specific symptoms. For each trial we recorded the strategy used and the number of potentially eligible participants excluded as a direct result of the chosen strategy. For each review we recorded the numbers of RCTs and participants excluded on the basis of symptoms experienced.

Results: There were 89 distinct PCOS trials in 13 reviews, and 13 Endometriosis trials in 11 reviews. Most trials restricted their eligibility to participants with specific symptoms (55% PCOS, 46% endometriosis). The second most common strategy was to measure and analyze clinical outcomes that were not relevant to all participants (38% PCOS, 31% endometriosis). Reviews excluded 27% of trials in participants evaluating the same intervention in participants experiencing the same condition based on the outcomes measured in the trials.

Conclusion: Most gynecological trials exclude patients who could benefit from treatment or measure outcomes not relevant to all participants. We introduce a taxonomy to describe trial design strategies for conditions with heterogeneous symptoms.

Keywords: Cochrane review; Gynecology; Outcome selection; Randomized clinical trial; Research waste; Trial design.