Sex Differences in Long-Term Functional Decline after Ischemic Stroke: A Longitudinal Observational Study from the Fukuoka Stroke Registry

Introduction: Data on sex differences in poststroke functional status for a period longer than 1 year based on large cohorts are sparse. This study aimed to determine whether there are sex differences in long-term functional decline after ischemic stroke. Methods: We tracked functional status for 5 years among 3-month survivors of acute ischemic stroke and compared outcomes between women and men using a large-scale hospital-based stroke registry in Fukuoka, Japan. Functional status was assessed using the modified Rankin Scale (mRS). Functional dependency was defined as an mRS score of 3, 4, or 5. Logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals of outcomes after adjusting for possible confounders. Results: A total of 8,446 patients (71.9 +/- 12.5 years, 3,377 (40.0%) female patients) were enrolled in this study. Female sex was associated with a higher risk of functional dependency at 5 years poststroke even when adjusting for age, 3-month mRS score, and other confounding factors (multivariable-adjusted OR vs. men, 1.56 [95% confidence interval, 1.26-1.93]). This significant association of female sex with higher dependency at 5 years was also found among patients who were independent at 3 months poststroke. Subgroup analysis showed that increased risk of functional dependency in female patients was more marked in patients aged >= 75 years than in those aged <75 years (p for heterogeneity = 0.02). Conversely, female sex was associated with a lower risk of death. No sex difference was observed in stroke recurrence during 5 years poststroke. Discussion/Conclusion: This longitudinal observational study suggests that female sex was independently associated with an increased risk of functional decline in the chronic phase of stroke, especially in older patients. There was no sex difference in 5-year stroke recurrence, and thus, other factors might be involved in more significant deterioration of functional status in female survivors of ischemic stroke. Further studies are needed to elucidate underlying causes of sex differences in long-term functional decline after stroke.