Association Between Excess Leisure Sedentary Time and Risk of Stroke in Young Individuals

Background and Purpose: The association between physical activity (PA) and lower risk of stroke is well established, but the relationship between leisure sedentary time and stroke is less well studied. Methods: We used 9 years of the Canadian Community Health Survey between 2000 and 2012 to create a cohort of healthy individuals without prior stroke, heart disease, or cancer. We linked to hospital records to determine subsequent hospitalization or emergency department visit for stroke until December 31, 2017. We quantified the association between self-reported leisure sedentary time (categorized as <4, 4 to <6, 6 to <8, and 8+ hours/day) and risk of stroke using Cox regression models and competing risk regression, assessing for modification by PA, age, and sex and adjusting for demographic, vascular, and social factors. Results: There were 143 180 people in our cohort and 2965 stroke events in follow-up. Median time from survey response to stroke was 5.6 years. There was a 3-way interaction between leisure sedentary time, PA, and age. The risk of stroke with 8+ hours of sedentary time was significantly elevated only among individuals <60 years of age who were in the lowest PA quartile (fully adjusted hazard ratio, 4.50 [95% CI, 1.64–12.3]). The association was significant across multiple sensitivity analyses, including adjustment for mood disorders and when accounting for the competing risk of death. Conclusions: Excess leisure sedentary time of 8+ hours/day is associated with increased risk of long-term stroke among individuals <60 years of age with low PA. These findings support efforts to enhance PA and reduce sedentary time in younger individuals.