Individual participant data meta-analyses should not ignore clustering

Abo-Zaid, Ghada and Guo, Boliang and Deeks, Jonathan J. and Debray, Thomas P.A. and Steyerberg, Ewout W. and Moons, Karel G.M. and Riley, Richard David (2013) Individual participant data meta-analyses should not ignore clustering. Journal of Clinical Epidemiology, 66 (8). 865-873.e4. ISSN 1878-5921

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Abstract

Objectives

Individual participant data (IPD) meta-analyses often analyze their IPD as if coming from a single study. We compare this approach with analyses that rather account for clustering of patients within studies.

Study Design and Setting

Comparison of effect estimates from logistic regression models in real and simulated examples.

Results

The estimated prognostic effect of age in patients with traumatic brain injury is similar, regardless of whether clustering is accounted for. However, a family history of thrombophilia is found to be a diagnostic marker of deep vein thrombosis [odds ratio, 1.30; 95% confidence interval (CI): 1.00, 1.70; P = 0.05] when clustering is accounted for but not when it is ignored (odds ratio, 1.06; 95% CI: 0.83, 1.37; P = 0.64). Similarly, the treatment effect of nicotine gum on smoking cessation is severely attenuated when clustering is ignored (odds ratio, 1.40; 95% CI: 1.02, 1.92) rather than accounted for (odds ratio, 1.80; 95% CI: 1.29, 2.52). Simulations show models accounting for clustering perform consistently well, but downwardly biased effect estimates and low coverage can occur when ignoring clustering.

Conclusion

Researchers must routinely account for clustering in IPD meta-analyses; otherwise, misleading effect estimates and conclusions may arise.

Item Type: Article
Schools/Departments: University of Nottingham UK Campus > Faculty of Medicine and Health Sciences > School of Medicine > Division of Psychiatry
Identification Number: https://doi.org/10.1016/j.jclinepi.2012.12.017
Depositing User: Guo, Dr Boliang
Date Deposited: 03 Feb 2016 14:39
Last Modified: 15 Sep 2016 06:04
URI: http://eprints.nottingham.ac.uk/id/eprint/31498

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