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OBJECTIVES:The objective of this study was to assess the uptake of the rheumatoid arthritis core outcome set (RA-COS) using data from multiple data providers, and to investigate factors that may influence this uptake. STUDY DESIGN AND SETTING:An observational review was carried out on all clinical trials of rheumatoid arthritis that were indexed on the World Health Organization-International Clinical Trials Registry Platform (WHO-ICTRP). Various measures of COS uptake were calculated from information presented in the trial registries and trial publications. Logistic regression was conducted to investigate factors thought to be associated with planned COS uptake. RESULTS:A total of 341 trials were eligible for the evaluation of RA-COS uptake. In the decade leading up to 2019, the assessment of uptake based on published results was maintained at just over 80%. Trials that were not commercially funded were much less likely to plan to measure the RA-COS than those with industry funding (60% vs. 80%; adjusted OR 0.18, 95% CI 0.11 to 0.32; P < 0.001). CONCLUSION:This study has demonstrated that the use of the WHO-ICTRP can identify a large and geographically diverse range of trials to include in the evaluation of COS uptake.

Original publication




Journal article


Journal of clinical epidemiology

Publication Date





90 - 97


Department of Biostatistics, University of Liverpool, Liverpool, UK; Centre for Biostatistics, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK. Electronic address: