Methodology

Covariate balance in a Bayesian propensity score analysis of beta blocker therapy in heart failure patients

Lawrence C McCandless¹ , Paul Gustafson² , Peter C Austin^3,4,5 and Adrian R Levy⁶

¹  Faculty of Health Sciences, Simon Fraser University, Canada

²  Department of Statistics, University of British Columbia, Canada

³  Institute for Clinical Evaluative Sciences, Toronto, Canada

⁴  Dalla Lana School of Public Health, University of Toronto, Canada

⁵  Department of Health Policy, Management and Evaluation, University of Toronto, Canada

⁶  School of Population and Public Health, University of British Columbia, Canada

author email corresponding author email

Epidemiologic Perspectives & Innovations 2009, 6:5doi:10.1186/1742-5573-6-5

Published:	10 September 2009

Abstract

Regression adjustment for the propensity score is a statistical method that reduces confounding from measured variables in observational data. A Bayesian propensity score analysis extends this idea by using simultaneous estimation of the propensity scores and the treatment effect. In this article, we conduct an empirical investigation of the performance of Bayesian propensity scores in the context of an observational study of the effectiveness of beta-blocker therapy in heart failure patients. We study the balancing properties of the estimated propensity scores. Traditional Frequentist propensity scores focus attention on balancing covariates that are strongly associated with treatment. In contrast, we demonstrate that Bayesian propensity scores can be used to balance the association between covariates and the outcome. This balancing property has the effect of reducing confounding bias because it reduces the degree to which covariates are outcome risk factors.