COMPARISON OF METAANALYSIS VERSUS ANALYSIS OF VARIANCE OF INDIVIDUAL PATIENT DATA

Meta-analysis is a method of synthesizing the results of independent s tudies. We consider the case in which there are multiple treatments an d a control, with the goal of estimating the relative effect of each t reatment based on continuous outcomes. Even when all data are availabl e, rather than only summary data, it has become common to use meta-ana lytic estimators of treatment contrasts. Alternatively, we could use a two-way analysis of variance model with no interaction in which one f actor is study and one factor is treatment. For the unbalanced case, w e obtain the surprising result that the standard meta-analysis estimat es of treatment contrasts are identical to the least squares estimator s of treatment contrasts in the linear model. Because a meta-analysis of individual patient data can be considerably more costly in terms of data retrieval than a meta-analysis of summary data, this equivalence provides for cost-efficient analysis.