Association between post-stroke disability and 5-year hip-fracture risk: The Women's Health Initiative

Background: Hip fractures are a significant post-stroke complication. We examined predictors of hip fracture risk after stroke using data from the Women's Health Initiative (WHI). In particular, we examined the association between post-stroke disability levels and hip fracture risk. Methods: The WHI is a prospective study of 161,808 postmenopausal women aged 50-79 years. Trained physicians adjudicated stroke events and hip fractures. Our study included stroke survivors from the observational and clinical trial arms who had a Glasgow Outcome Scale of good recovery, moderately disabled, or severely disabled and survived more than 7 days post-stroke. Hip fracture-free status was compared across disability levels. Secondary analysis examined hip fracture risk while accounting for competing risk of death. Results: Average age at time of stroke was 74.6±7.2 years; 84.3% were white. There were 124 hip fractures among 4,640 stroke survivors over a mean follow-up time of 3.1±1.8 years. Mortality rate was 23.3%. Severe disability at discharge (Hazard Ratio (HR): 2.1 (95% Confidence Interval (CI): 1.4-3.2), but not moderate disability (HR: 1.1 (95%CI: 0.7-1.7), was significantly associated with an increased risk of hip fracture compared to good recovery status. This association was attenuated after accounting for mortality. White race, increasing age and higher Fracture Risk Assessment Tool (FRAX)-predicted hip fracture risk (without bone density information) were associated with an increased hip fracture risk. After accounting for mortality, higher FRAX risk and white race remained significant. Conclusion: Severe disability after stroke and a higher FRAX risk score were associated with risk of subsequent hip fracture. After accounting for mortality, only the FRAX risk score remained significant. The FRAX risk score appears to identify stroke survivors at high risk of fractures. Our results suggest that stroke units can consider the incorporation of osteoporosis screening into care pathways.