Meta-research on patient-reported outcomes in trial protocols and results publications suggested large outcome reporting bias

Objectives Patient-reported outcomes (PROs) provide crucial information for evaluating health-care interventions, but previous research in specific disease areas suggested infrequent use and incomplete reporting of PROs. We examined the prevalence and characteristics of PROs in randomized clinical trial (RCT) protocols across medical fields, their reporting quality, and the consistency between PROs specified in trial protocols and subsequent reporting in trial publications. Study Design And Setting We included 237 RCT protocols approved in 2012 and 251 approved in 2016, by ethics committees in Switzerland, Germany, and Canada. We systematically searched for corresponding peer-reviewed results publications and results on trial registries. Pairs of reviewers independently extracted characteristics of RCT protocols, PROs specified in protocols and reported in corresponding results publications, and assessed the reporting quality of RCTs with a PRO as the primary outcome using the Consolidated Standards of Reporting Trials-patient-reported outcome (CONSORTs-PRO) extension. Results Out of 488 included RCT protocols, 147 (30%) did not report use of a PRO; 97 (20%) specified a PRO as the primary outcome and an additional 244 (50%) as a secondary outcome. The prevalence of PROs varied substantially across medical fields, ranging from 100% in rheumatology and psychiatry to about one-third in cardiology and anesthesiology. At 8-10 years after RCT approval, results were available for 264 of the 341 (77%) trial protocols that prespecified PROs. Forty-four percent of the published trials (115/264) reported all PROs as defined in the protocol, 21% (55/264) did not report any prespecified PROs, and 36% (94/264) reported more, fewer, or different PROs than those prespecified. These findings were consistent between trial protocols approved in 2012 and 2016. Among 63 peer-reviewed RCT publications that reported a PRO as their primary outcome, reporting quality was often inadequate, with seven of 13 CONSORT-PRO items. Conclusion Less than half of RCT protocols with planned PROs reported them as specified in corresponding published results, suggesting outcome reporting bias, and PRO reporting quality was often deficient. These limitations complicate informed decision-making between patients and health-care providers, as well as the development of evidence-based clinical practice guidelines.