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Empirical comparison of subgroup effects in conventional and individual patient data meta-analyses

Published online by Cambridge University Press:  04 July 2008

Laura Koopman ,
Geert J. M. G. van der Heijden ,
Arno W. Hoes ,
Diederick E. Grobbee  and
Maroeska M. Rovers
Laura Koopman
Affiliation:
University Medical Center Utrecht
Geert J. M. G. van der Heijden
Affiliation:
University Medical Center Utrecht
Arno W. Hoes
Affiliation:
University Medical Center Utrecht
Diederick E. Grobbee
Affiliation:
University Medical Center Utrecht
Maroeska M. Rovers
Affiliation:
University Medical Center Utrecht
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Abstract

Objectives: Individual patient data (IPD) meta-analyses have been proposed as a major improvement in meta-analytic methods to study subgroup effects. Subgroup effects of conventional and IPD meta-analyses using identical data have not been compared. Our objective is to compare such subgroup effects using the data of six trials (n = 1,643) on the effectiveness of antibiotics in children with acute otitis media (AOM).

Methods: Effects (relative risks, risk differences [RD], and their confidence intervals [CI]) of antibiotics in subgroups of children with AOM resulting from (i) conventional meta-analysis using summary statistics derived from published data (CMA), (ii) two-stage approach to IPD meta-analysis using summary statistics derived from IPD (IPDMA-2), and (iii) one-stage approach to IPD meta-analysis where IPD is pooled into a single data set (IPDMA-1) were compared.

Results: In the conventional meta-analysis, only two of the six studies were included, because only these reported on relevant subgroup effects. The conventional meta-analysis showed larger (age < 2 years) or smaller (age ≥ 2 years) subgroup effects and wider CIs than both IPD meta-analyses (age < 2 years: RDCMA -21 percent, RDIPDMA-1 -16 percent, RDIPDMA-2 -15 percent; age ≥2 years: RDCMA -5 percent, RDIPDMA-1 -11 percent, RDIPDMA-2 -11 percent). The most important reason for these discrepant results is that the two studies included in the conventional meta-analysis reported outcomes that were different both from each other and from the IPD meta-analyses.

Conclusions: This empirical example shows that conventional meta-analyses do not allow proper subgroup analyses, whereas IPD meta-analyses produce more accurate subgroup effects. We also found no differences between the one- and two-stage meta-analytic approaches.

Keywords

Conventional meta-analysesIndividual patient data meta-analysesSubgroup analysesMeta-analyses methods
Type
RESEARCH REPORTS
Information
International Journal of Technology Assessment in Health Care , Volume 24 , Issue 3 , July 2008 , pp. 358 - 361
Copyright
Copyright © Cambridge University Press 2008

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