Extracted data from a comprehensive review of parallel group multi-arm trials published in the NIHR online Journals Library

The United Kingdom’s National Institute for Health and Care Research (NIHR) online Journals Library, was searched from 1 January 1997 to 31 December 2024 for reports of multi-arm RCTs. Extracted information includes: trial characteristics, the sample size estimation and analysis of the primary outcome. Search and selection was conducted by two researchers. Data extraction was conducted independently by two reviewers. Any arising disagreement or uncertainty was resolved by discussion.A total of 2452 reports were screened for eligibility, 97 reports of multi-arm parallel-group trials met the inclusion criteria, of these 90 included the results of a multi-arm efficacy analysis. This dataset includes the extracted data for all 97 multi-arm parallel-group trials.