Appraising between-study homogeneity, small-study effects, moderators, and confounders

Abstract

Meta-analysis is the statistical synthesis of results from two or more clinical studies that address the same issue and compare two different interventions. Although the combination of results of several studies in a meta-analysis can increase power and improve precision, caution is needed in the presence of between-study heterogeneity and selection bias. These two factors can importantly impact meta-analysis conclusions and hence influence decision-making. Several methods have been developed to appraise the between-study variation and the tendency of small studies to yield larger intervention effects compared to larger studies. This chapter presents an overall review of methods presented in the meta-analysis literature along with their properties.