Research and scholarly methods: Propensity scores.

Propensity score methods are increasingly used as a tool to control for confounding bias in pharmacoepidemiologic studies. The propensity score is a dimension reducing balancing score, creating treatment and reference groups that have comparable distributions of measured covariates. The purpose of this methods review is to provide an overview of the use of propensity score methods, including a summary of important data assumptions, various applications of the propensity score, and how to evaluate covariate balance. This article is intended for pharmacists and researchers who wish to receive an introduction to propensity score methods and be able to engage in high-level discussions on application and reporting.