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Two-stage or not two-stage? That is the question for IPD meta-analysis projects

Riley, Richard D; Ensor, Joie; Hattle, Miriam; Papadimitropoulou, Katerina; Morris, Tim P; (2023) Two-stage or not two-stage? That is the question for IPD meta-analysis projects. Research Synthesis Methods 10.1002/jrsm.1661. (In press). Green open access

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Abstract

Individual participant data meta-analysis (IPDMA) projects obtain, check, harmonise and synthesise raw data from multiple studies. When undertaking the meta-analysis, researchers must decide between a two-stage or a one-stage approach. In a two-stage approach, the IPD are first analysed separately within each study to obtain aggregate data (e.g., treatment effect estimates and standard errors); then, in the second stage, these aggregate data are combined in a standard meta-analysis model (e.g., common-effect or random-effects). In a one-stage approach, the IPD from all studies are analysed in a single step using an appropriate model that accounts for clustering of participants within studies and, potentially, between-study heterogeneity (e.g., a general or generalised linear mixed model). The best approach to take is debated in the literature, and so here we provide clearer guidance for a broad audience. Both approaches are important tools for IPDMA researchers and neither are a panacea. If most studies in the IPDMA are small (few participants or events), a one-stage approach is recommended due to using a more exact likelihood. However, in other situations, researchers can choose either approach, carefully following best practice. Some previous claims recommending to always use a one-stage approach are misleading, and the two-stage approach will often suffice for most researchers. When differences do arise between the two approaches, often it is caused by researchers using different modelling assumptions or estimation methods, rather than using one or two stages per se.

Type: Article
Title: Two-stage or not two-stage? That is the question for IPD meta-analysis projects
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/jrsm.1661
Publisher version: https://doi.org/10.1002/jrsm.1661
Language: English
Additional information: © 2023 The Authors. Research Synthesis Methods published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).
Keywords: individual participant data (IPD), meta-analysis, one-stage approach, two-stage approach
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology > MRC Clinical Trials Unit at UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10175670
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