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Main Authors: McGuinness, Myra B., McKenzie, Joanne E., Forbes, Andrew, Hui, Flora, Martin, Keith R., Casson, Robert J., Karahalios, Amalia
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2510.24130
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author McGuinness, Myra B.
McKenzie, Joanne E.
Forbes, Andrew
Hui, Flora
Martin, Keith R.
Casson, Robert J.
Karahalios, Amalia
author_facet McGuinness, Myra B.
McKenzie, Joanne E.
Forbes, Andrew
Hui, Flora
Martin, Keith R.
Casson, Robert J.
Karahalios, Amalia
contents It is recommended that measures of between-study effect heterogeneity be reported when conducting individual-participant data meta-analyses (IPD-MA). Methods exist to quantify inconsistency between trials via I^2 (the percentage of variation in the treatment effect due to between-study heterogeneity) when conducting two-stage IPD-MA, and when conducting one-stage IPD-MA with approximately equal numbers of treatment and control group participants. We extend formulae to estimate I^2 when investigating treatment-covariate interactions with unequal numbers of participants across subgroups and/or continuous covariates. A simulation study was conducted to assess the agreement in values of I^2 between those derived from two-stage models using traditional methods and those derived from equivalent one-stage models. Fourteen scenarios differed by the magnitude of between-trial heterogeneity, the number of trials, and the average number of participants in each trial. Bias and precision of I^2 were similar between the one- and two-stage models. The mean difference in I^2 between equivalent models ranged between -1.0 and 0.0 percentage points across scenarios. However, disparities were larger in simulated datasets with smaller samples sizes with up to 19.4 percentage points difference between models. Thus, the estimates of I^2 derived from these extended methods can be interpreted similarly to those from existing formulae for two-stage models.
format Preprint
id arxiv_https___arxiv_org_abs_2510_24130
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantifying inconsistency in one-stage individual participant data meta-analyses of treatment-covariate interactions: a simulation study
McGuinness, Myra B.
McKenzie, Joanne E.
Forbes, Andrew
Hui, Flora
Martin, Keith R.
Casson, Robert J.
Karahalios, Amalia
Methodology
It is recommended that measures of between-study effect heterogeneity be reported when conducting individual-participant data meta-analyses (IPD-MA). Methods exist to quantify inconsistency between trials via I^2 (the percentage of variation in the treatment effect due to between-study heterogeneity) when conducting two-stage IPD-MA, and when conducting one-stage IPD-MA with approximately equal numbers of treatment and control group participants. We extend formulae to estimate I^2 when investigating treatment-covariate interactions with unequal numbers of participants across subgroups and/or continuous covariates. A simulation study was conducted to assess the agreement in values of I^2 between those derived from two-stage models using traditional methods and those derived from equivalent one-stage models. Fourteen scenarios differed by the magnitude of between-trial heterogeneity, the number of trials, and the average number of participants in each trial. Bias and precision of I^2 were similar between the one- and two-stage models. The mean difference in I^2 between equivalent models ranged between -1.0 and 0.0 percentage points across scenarios. However, disparities were larger in simulated datasets with smaller samples sizes with up to 19.4 percentage points difference between models. Thus, the estimates of I^2 derived from these extended methods can be interpreted similarly to those from existing formulae for two-stage models.
title Quantifying inconsistency in one-stage individual participant data meta-analyses of treatment-covariate interactions: a simulation study
topic Methodology
url https://arxiv.org/abs/2510.24130