Sex differences in the impact of acute stroke treatment in a population-based study: a sex-specific propensity score approach

Purpose: We investigated whether sex modifies the association of acute stroke treatment on functional outcome using propensity score (PS) methods to minimize confounding and to explore the differential effects of confounders by sex. Methods: We included tissue plasminogen activator (tPA) treated (n = 84) and nontreated ischemic stroke cases (n = 143) from a population-based stroke study (2008-2013). The PS model that estimated the probability of receiving tPA included interactions between sex and treatment predictors. The outcome model included sex, tPA, and their interaction. In addition, sex-specific PS values were included as a continuous covariate and modeled using splines. We compared the results with conventional methods of statistical adjustment. Results: Conventional methods of adjustment suggested that women receive greater benefit from tPA than men. After taking into consideration that the influence of confounders, specifically age and stroke severity, differed by sex, we found no sex difference in the tPA-functional outcome association (P =.94). Conclusions: Using PS methods that considered confounding of the sex x treatment interaction, we did not find that the association of tPA with functional outcome differed for women and men. Our findings may have implications for the methodologic approaches used to address confounding in studies that seek to compare stroke treatment effects by sex. (C) 2017 Elsevier Inc. All rights reserved.