Impact of changes in physical activity and incident fracture after acute ischemic stroke

Stroke survivors are at an increased risk of falls and fractures. Physical activity is inversely associated with the fracture risk in the general population. However, the association between incident fracture risk and changes in habitual physical activity before and after an index stroke remains unclear. This study attempted to explore the association between incident fracture risk and changes in physical activity after stroke. Using the claims database of the National Health Insurance Program in Korea, participants with their first ischemic stroke between 2010 and 2016 were enrolled in the study. The participants were divided into four groups according to changes in physical activity habits evaluated using two consecutive self-reported questionnaires before and after stroke, if available: persistent non-exercisers, exercise dropouts, new exercisers, and persistent exercisers. The primary outcome was a composite of vertebral, hip, and other fractures. We performed multivariable Cox proportional hazard regression analysis and provided adjusted hazard ratios and 95% confidence intervals for each outcome. Among 202,234 participants included from 1,005,879 datasets, 16,621 (8.22%) experienced any type of fracture as the primary outcome. After multivariable adjustment, exercise dropouts (n = 37,106), new exercisers (n = 36,821), and persistent exercisers (n = 74,647) had a significantly reduced risk of any type of fracture (aHR 0.932, 95% CI 0.893-0.973; aHR 0.938, 95% CI 0.900-0.978; aHR 0.815, 95% CI 0.780-0.852, respectively) compared to the persistent non-exercisers (n = 53,660). Furthermore, regardless of pre-stroke exercise status, those who exercised ≥ 1000 metabolic equivalents of tasks post-stroke had a significantly reduced risk of fractures. Initiating or continuing moderate-to-vigorous regular physical activity after acute ischemic stroke was associated with a significantly lower risk of incident fractures, including hip, vertebral, and other types.