Keele Research Repository

Riley, RD ORCID: https://orcid.org/0000-0001-8699-0735, Legha, A ORCID: https://orcid.org/0000-0001-7389-5384, Jackson, D, Morris, TP, Ensor, J ORCID: https://orcid.org/0000-0001-7481-0282, Snell, KIE ORCID: https://orcid.org/0000-0001-9373-6591, White, IR and Burke, DL ORCID: https://orcid.org/0000-0003-2803-1151 (2020) One-stage individual participant data meta-analysis models for continuous and binary outcomes: comparison of treatment coding options and estimation methods. Statistics in Medicine.

Text Treatment Coding - ACCEPTED 3rd March 2020.docx - Accepted Version Restricted to Repository staff only until 11 May 2021. Available under License Creative Commons Attribution Non-commercial. Download (1MB)

Abstract

A one-stage individual participant data (IPD) meta-analysis synthesises IPD from multiple studies using a general or generalised linear mixed model. This produces summary results (e.g. about treatment effect) in a single step, whilst accounting for clustering of participants within studies (via a stratified study intercept, or random study intercepts) and between-study heterogeneity (via random treatment effects). We use simulation to evaluate the performance of restricted maximum likelihood (REML) and maximum likelihood (ML) estimation of one-stage IPD meta-analysis models for synthesising randomised trials with continuous or binary outcomes. Three key findings are identified. Firstly, for ML or REML estimation of stratified intercept or random intercepts models, a t-distribution based approach generally improves coverage of confidence intervals for the summary treatment effect, compared to a z-based approach. Secondly, when using ML estimation of a one-stage model with a stratified intercept, the treatment variable should be coded using ‘study-specific centering’ (i.e. 1/0 minus the study-specific proportion of participants in the treatment group), as this reduces the bias in the between-study variance estimate (compared to 1/0 and other coding options). Thirdly, REML estimation reduces downward bias in between-study variance estimates compared to ML estimation, and does not depend on the treatment variable coding; for binary outcomes, this requires REML estimation of the pseudo-likelihood, although this may not be stable in some situations (e.g. when data are sparse). Two applied examples are used to illustrate the findings.

Item Type:	Article
Uncontrolled Keywords:	estimation methods; individual participant data; IPD; maximum likelihood; meta-analysis; treatment coding
Subjects:	H Social Sciences > H Social Sciences (General) H Social Sciences > HA Statistics
Divisions:	Faculty of Medicine and Health Sciences > School of Primary, Community and Social Care
Depositing User:	Symplectic
Date Deposited:	16 Apr 2020 15:58
Last Modified:	21 May 2020 10:19
URI:	https://eprints.keele.ac.uk/id/eprint/7876

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