Impact of sex in stroke thrombolysis: a coarsened exact matching study

BACKGROUND: It is not established whether sex influences outcome
and safety following intravenous thrombolysis (IVT) in acute
stroke. As a significant imbalance exists between the baseline
conditions of women and men, regression analysis alone may be
subject to bias. Here we aimed to overcome this methodical
shortcoming by balancing both groups using coarsened exact matching
(CEM) before evaluating outcome. METHODS: From our local
prospective stroke database we analyzed consecutive patients who
suffered anterior circulation stroke and received IVT from 1998 to
04/2013 (n = 1391, 668 female, 723 male). Data were preprocessed by
CEM, balancing for age, NIHSS, lesion side, hypertension, diabetes,
atrial fibrillation, smoking, coronary heart disease, and previous
stroke, which yielded a matched cohort of 502 women and 436 men
(n = 938). Outcome was estimated by adjusted binomial logistic
regression analysis incorporating matched weights. RESULTS: No
effect of sex was seen to predict good outcome (OR 1.04, CI
0.76-1.43) or mortality (OR 1.13, CI 0.73-1.73). However, female
sex was a strong independent predictor of symptomatic intracerebral
hemorrhage (sICH - ECASS-II definition, OR 3.62, CI 1.77-7.41) and
fatal ICH (OR 4.53, CI 1.61-12.7). CONCLUSION: In balanced groups,
the two sexes showed comparable outcomes following IVT. A novel
finding was the higher rate of sICH and fatal ICH in women. In this
analysis we also demonstrate how CEM can reduce multivariate
imbalance and thereby improve estimates, already in crude, but more
importantly, in adjusted regression analysis. Further
investigations of multicentre data with improved analytical
approaches that yield balanced sex-groups are therefore warranted.