title: Meta-Analysis of Effect Sizes Reported at Multiple Time Points Using General Linear Mixed Model.
abstract: Meta-analysis of longitudinal studies combines effect sizes measured at pre-determined time points. The most common approach involves performing separate univariate meta-analyses at individual time points. This simplistic approach ignores dependence between longitudinal effect sizes, which might result in less precise parameter estimates. In this paper, we show how to conduct a meta-analysis of longitudinal effect sizes where we contrast different covariance structures for dependence between effect sizes, both within and between studies. We propose new combinations of covariance structures for the dependence between effect size and utilize a practical example involving meta-analysis of 17 trials comparing postoperative treatments for a type of cancer, where survival is measured at 6, 12, 18 and 24 months post randomization. Although the results from this particular data set show the benefit of accounting for within-study serial correlation between effect sizes, simulations are required to confirm these results.
authors: School of Mathematics, Statistics, and Computer Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
authors: Alfred
authors: A
authors: Musekiwa
authors: School of Mathematics, Statistics, and Computer Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa.|Biostatistics Unit, South African Medical Research Council, Pretoria, South Africa.
authors: Samuel O M
authors: SO
authors: Manda
authors: School of Mathematics, Statistics, and Computer Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
authors: Henry G
authors: HG
authors: Mwambi
authors: School of Social Work, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.|Department of Statistics, University of Pretoria, Pretoria, South Africa.
authors: Ding-Geng
authors: DG
authors: Chen
mesh_terms: D000465:Algorithms; D003131:Combined Modality Therapy; D006801:Humans; D016013:Likelihood Functions; D016014:Linear Models; D008137:Longitudinal Studies; D015201:Meta-Analysis as Topic; D015233:Models, Statistical; D009369:Neoplasms / Q000401:mortality / Q000628:therapy; D016017:Odds Ratio; D011182:Postoperative Care; D012107:Research Design; D018401:Sample Size