Assessing the uptake of infertility core outcome set in IVF randomized controlled trials.

study questionDo the infertility core outcome set and standardized definitions affect the outcome selection for randomized controlled trials, and what aspects should be further improved in the future? SUMMARY ANSWER: Intrauterine pregnancy demonstrated the highest uptake level, whereas others were low, especially in neonatal outcomes; as time progresses, the target sample size increases, and with prospective registration, the consistency between outcomes reported in registrations and infertility core outcome set improves significantly. WHAT IS KNOWN ALREADY: The infertility core outcome set, published on 30 November 2020, aims to standardize outcome reporting and prevent selective reporting bias; however, there is a paucity of research evaluating its actual adoption, which is crucial for the timely promotion of transparency, standardization, adjustment of development strategies, and efficient resource utilization. STUDY DESIGN, SIZE, DURATION: This cross-sectional study included 1673 eligible randomized controlled trial registrations for infertility in 18 registries from March 2004 to July 2024 based on registry entries. PARTICIPANTS/MATERIALS, SETTING,

methodsA total of 4625 infertility-related studies from 1 November 1999 to 26 July 2024 were retrieved in the World Health Organization International Clinical Trials Registry Platform. Finally, 1673 randomized controlled trial registrations were selected and divided into four period groups. Period, target sample size, prospective registration, blinding, support, and countries/regions were potential influencing factors. The consistency of outcomes, definitions, and standardized denominators of randomized controlled trial registry entries with the recommendations of the infertility core outcome set were the main outcomes. Independent retrieval, screening, data extraction, and consistency evaluations by two assessors and expert consultations were conducted to assess the uptake and potential influencing factors of the infertility core outcome set in randomized controlled trials involving infertile patients undergoing in vitro fertilization. MAIN RESULTS AND THE ROLE OF CHANCE: Results reveal that the reporting level in the pregnancy domain was significantly higher than that in the neonatal domain (13.6% vs 5.7%). Intrauterine pregnancy (66.9%), live birth (27.6%), and miscarriage (26.5%) had relatively high uptake levels. The uptake of most core outcomes and domains, as well as the total number of reported core outcomes, showed statistically significant differences based on period, target sample size, and prospective registration. Multivariable analyses supported the above finding. Reasons responsible for the results may be attributed to the lack of effective promotional measures, as well as the limited researcher awareness regarding this core outcome set. LIMITATIONS, REASONS FOR CAUTION: Some results in this study may have been influenced by the subjective judgment of the evaluators due to the complexity of the information in registries. WIDER IMPLICATIONS OF THE

findingsUptake of most core outcomes or domains is increasing but is not yet ideal. Moreover, the upward trend cannot be solely attributed to the publication of the infertility core outcome set. The key to promoting uptake is to thoroughly explore and recognize the factors that both facilitate and hinder the uptake of the infertility core outcome set, further expand and publicize the core outcome set, and foster multidisciplinary or multiple stakeholder cooperation. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the Capital's Funds for Health Improvement and Research (CFH 2024-2G-4097), as well as the special fund of Beijing Key Clinical Specialty Construction Project. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: http://www.comet-initiative.org/Studies/Details/3184.