Trial participants are frequently excluded based on their symptoms rather than their condition: A systematic review of Cochrane reviews and their component trials

ObjectivesIdentify strategies used in the design of recent randomised controlled trials (RCTs) and their associated Cochrane reviews where patients with the same gynaecological condition present with different symptoms. Study Design and SettingWe 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. We restricted to trials published since 2012 to consider current approaches. For each trial we recorded 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 unnecessarily. ResultsThere 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 analyse clinical outcomes that were not relevant to all participants (38% PCOS, 31% endometriosis). Reviews excluded 27% of trials based just on outcome data. ConclusionsCurrent gynaecological research is inefficient. Most trials either exclude patients who could benefit from treatment or measure outcomes not relevant to all participants. RegistrationPROSPERO (CRD42022334776) What is new?O_ST_ABSKey findingsC_ST_ABSO_LIOver a quarter of Cochrane reviews included in this review excluded trials based on the outcomes reported. C_LIO_LITypically, recent randomised controlled trials in Polycystic Ovarian Syndrome and Endometriosis trials either exclude patients who could potentially benefit from the treatment given, or measure outcomes of no relevance to some participants. C_LI What this adds to what is known?O_LIStrategies developed that are employed in the design and measurement of outcomes in gynaecological trials. C_LIO_LIThere are multiple sources of waste in the current gynaecological research landscape. The population of patients available is under-utilised by excluding patients based on the outcomes measured, or alternatively, researchers are measuring outcomes in patients who do not experience the associated symptom(s). C_LI What is the implication and what should change now?O_LIGynaecological patients experience heterogeneity in their symptoms and therefore it is crucial to employ appropriate outcome measures in order to reduce research waste. Cochrane Reviews should include all trials which report outcomes that are relevant to the population of interest if the intervention under investigation is deemed to plausibly treat the associated symptom(s). C_LI