Effect Modification Analyses in Individual Participant Data Meta-Analyses

How often are effect modification analyses in individual participant data meta-analyses (IPDMAs) of randomized clinical trials planned and prespecified?In this systematic review of 356 IPDMA protocols and 166 matching published reports, 94% of protocols planned effect modification analyses, but only 4% specified the anticipated direction of effect and 11% explicitly planned within-trial analyses. Among matched protocol-report pairs, only 19% showed complete agreement on the number and factors of effect modification analyses; 77% of reports omitted at least 1 planned analysis, and 60% included unplanned analyses.The findings of this study suggest that effect modification analyses in IPDMAs often lack prespecification and concordance between protocols and reports, which may undermine transparency and reproducibility.

Corresponding Authors: Junhua Zhang, PhD, Evidence-Based Medicine Center, Tianjin University of Traditional Chinese Medicine, 312 Anshanxi Str, Tianjin 300193, China (zjhtcm@foxmail.com); Jinhui Tian, PhD, Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China (tianjh@lzu.edu.cn).

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