Interpreting Geographic Variations in Results of Randomized, Controlled Trials

Abstract

Conslusions: Although most variations in results among countries are probably due to chance, variations can occasionally reflect important differences among countries in either the true benefits of an intervention or its true harms. When a randomized, clinical trial shows marked variations in results among countries, one should seek supporting evidence to understand whether the observed results are likely to be real, an artifact of the design analysis or implementation of the trial, or simply due to chance.