On the utility of the Dirichlet distribution for meta-analysis of clinical studies.

Recently, there has been an increasing interest in combining efficacy (or safety) results from several clinical trials to draw an overall conclusion about the efficacy (or safety) of new investigational drugs. In a two-armed clinical trial, these efficacy outcomes are often expressed in terms of the two treatment effect means or the proportions of treatment success. For several clinical trials, efficacy assessment could be based on different types of clinical outcomes. These outcomes might be both categorical and noncategorical. Therefore, it is desirable to have a statistical model that is flexible enough for combining clinical trial data of both outcomes across several trials or studies. We discuss a simple statistical model with a potential for such flexibility. We illustrate the use of the model by providing a couple of numerical examples on the meta-analyses of efficacy data from prospective clinical trials/studies.