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Meta-analysis when only the median survival times are known: A comparison with individual patient data results

Published online by Cambridge University Press:  02 March 2005

Stefan Michiels ,
Pascal Piedbois ,
Sarah Burdett ,
Nathalie Syz ,
Lesley Stewart  and
Jean-Pierre Pignon
Stefan Michiels
Affiliation:
Institut Gustave-Roussy
Pascal Piedbois
Affiliation:
Henri Mondor Hospital
Sarah Burdett
Affiliation:
MRC Clinical Trials Unit
Nathalie Syz
Affiliation:
Institut Gustave-Roussy
Lesley Stewart
Affiliation:
MRC Clinical Trials Unit
Jean-Pierre Pignon
Affiliation:
Institut Gustave-Roussy
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Abstract

Background: The hazard ratio (HR) is the most appropriate measure for time to event outcomes such as survival. In systematic reviews, HRs can be calculated either from the raw trial data obtained as part of an individual patient data (IPD) meta-analysis or from the appropriate trial-level summary statistics. However, the information required for the latter are seldom reported in sufficient detail to allow reviewers to calculate HRs. In contrast, the median survival and survival rates at specific time points are frequently presented. We aimed to evaluate retrospectively the performance of meta-analyses using median survival times and survival rates by comparing them with meta-analyses using IPD to calculate HRs.

Methods: IPD from thirteen published meta-analyses (MAs) in cancers with high mortality rates were used. Median survival and survival rates were calculated from the IPD rather than taken from publications so that the same trials, patients, and extended follow-up are used in each analysis.

Results and Conclusions: We show that using median survival times or survival rates at a particular point in time are not reasonable surrogate measures for meta-analyses of survival outcomes and that, wherever possible, HRs should be calculated. Individual trial publications reporting on time to event outcomes, therefore, should provide more detailed statistical information, preferably logHRs and their variances, or their estimators.

Keywords

Meta-analysisSummary dataMedian survival timeSurvival analysisTime to event outcomes
Type
RESEARCH REPORTS
Information
International Journal of Technology Assessment in Health Care , Volume 21 , Issue 1 , January 2005 , pp. 119 - 125
Copyright
© 2005 Cambridge University Press

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