Research waste among randomized controlled trials in ovarian cancer: A cross-sectional study

Objective: To examine the association between trial characteristics and research waste in randomized controlled trials (RCTs) on ovarian cancer over the past two decades. Methods: ClinicalTrials.gov was searched for RCTs registered between 2000 and 2020 using the keyword ovarian cancer. Publication status of RCTs was determined through systematic searches of the PubMed and Google Scholar databases. Reporting adequacy was evaluated using the CONSORT checklist. Design limitations were assessed based on the risk of bias and whether a relevant systematic review was cited in the manuscript. The primary outcome was research waste, defined as an RCT that was unpublished, inadequately reported, or had avoidable design limitations. Results: Among the 117 RCTs evaluated, 89 (76.1 %) were published as of February 14, 2024. Published RCTs were more likely to be pharmacological, conducted in North America or Europe, have a multicenter or multinational design, have a larger sample size (over 200 participants), and receive external funding (P < 0.05). Among the published RCTs, 73 (82.0 %) and 24 (27.0 %) were considered adequately reported and free from design limitations, respectively. Overall, 96 of the 117 RCTs (82.1 %) were associated with research waste. Factors independently associated with research waste were an open -label design and smaller sample size (P < 0.05). Conclusion: Over 80 % of the RCTs on ovarian cancer demonstrated at least one feature of research waste. Future efforts should focus on minimizing the potential waste in unblinded small-scale RCTs.