Factors contributing to sex differences in functional outcomes and participation after stroke.

OBJECTIVE: To examine factors contributing to the sex differences in functional outcomes and participation restriction after stroke. METHODS: Individual participant data on long-term functional outcome or participation restriction (i.e., handicap) were obtained from 11 stroke incidence studies (1993-2014). Multivariable log-binomial regression was used to estimate the female:male relative risk (RR) of poor functional outcome (modified Rankin Scale score >2 or Barthel Index score <20) at 1 year (10 studies, n = 4,852) and 5 years (7 studies, n = 2,226). Multivariable linear regression was used to compare the mean difference (MD) in participation restriction by use of the London Handicap Scale (range 0-100 with lower scores indicating poorer outcome) for women compared to men at 5 years (2 studies, n = 617). For each outcome, study-specific estimates adjusted for confounding factors (e.g., sociodemographics, stroke-related factors) were combined with the use of random-effects meta-analysis. RESULTS: In unadjusted analyses, women experienced worse functional outcomes after stroke than men (1 year: pooled RRunadjusted 1.32, 95% confidence interval [CI] 1.18-1.48; 5 years: RRunadjusted 1.31, 95% CI 1.16-1.47). However, this difference was greatly attenuated after adjustment for age, prestroke dependency, and stroke severity (1 year: RRadjusted 1.08, 95% CI 0.97-1.20; 5 years: RRadjusted 1.05, 95% CI 0.94-1.18). Women also had greater participation restriction than men (pooled MDunadjusted -5.55, 95% CI -8.47 to -2.63), but this difference was again attenuated after adjustment for the aforementioned factors (MDadjusted -2.48, 95% CI -4.99 to 0.03). CONCLUSIONS: Worse outcomes after stroke among women were explained mostly by age, stroke severity, and prestroke dependency, suggesting these potential targets to improve the outcomes after stroke in women.