Physical inactivity is a strong risk factor for stroke in the oldest old: Findings from a multi-ethnic population (the Northern Manhattan Study)

Background: The fastest growing segment of the population is those age ≥80 who have the highest stroke incidence. Risk factor management is complicated by polypharmacy-related adverse events. Aims: To characterize the impact of physical inactivity for stroke by age in a multi-ethnic prospective cohort study (NOMAS, n = 3298). Methods: Leisure time physical activity was assessed by a validated questionnaire and our primary exposure was physical inactivity (PI). Participants were followed annually for incident stroke. We fit Cox-proportional hazard models to calculate hazard ratios and 95% confidence intervals (HR 95% CI) for the association of PI and other risk factors with risk of stroke including two-way interaction terms between the primary exposures and age (<80 vs. ≥80). Results: The mean age was 69 ± 10.3 years and 562 (17%) were ≥80 at enrolment. PI was common in the cohort (40.8%). Over a median of 14 years, we found 391 strokes. We found a significant interaction of age ≥80 on the risk of stroke with PI (p = 0.03). In stratified models, PI versus any activity (adjusted HR 1.60, 95%CI 1.05–2.42) was associated with an increased risk of stroke among those ≥80. Conclusion: Physical inactivity is a treatable risk factor for stroke among those older than age 80. Improving activity may reduce the risk of stroke in this segment of the population.