Introduction: The fastest growing segment of the population is those over age 80, in whom there is the highest incidence of stroke. Few clinical trials, however, have targeted this population, and management of risk factors is complicated by higher rates of side effects and polypharmacy. We aimed to characterize whether the risk factors for stroke are different in those age >80 versus <80 in a multi-ethnic prospective cohort study.
Methods: The study sample derives from the Northern Manhattan Study (n=3298), a prospective cohort study among an urban dwelling multi-ethnic population. At enrollment risk factors were assessed by self-report, physical examination, and laboratory data. Leisure-time physical activity (LTPA) was assessed by validated questionnaire and categorized as none versus any. Participants are followed annually for incident stroke which is adjudicated by study neurologists after review of all records and imaging. We fit Cox proportional hazard models to calculate hazard ratios (HR) and 95% confidence intervals (95% CI) for the association of cardiovascular disease risk factors (LTPA, reported alcohol use, fasting HDL-C and LDL-C, history of diabetes, hypertension, heart disease, and tobacco use) with risk of stroke. Multi-variable models also included two-way interaction terms between the primary exposures and age (<80 and ≥80) and stratified models are presented if p-interaction < 0.05.
Results: The mean age was 69 years and 562 (17%) were age ≥80 years. Physical inactivity was common (41%) and did not differ by age. Subjects were followed for a median of 14 years, and there were 391 total strokes. We found a statistically significant interaction of age ≥80 on the risk of stroke with physical inactivity (p=0.02), diabetes (p=0.04), hypertension (p=0.005), and LDL-C (p=0.03). In stratified models no LTPA versus any (adjusted HR 1.61, 95%CI 1.06-2.43) was associated with an increased risk of stroke among those age ≥80 but not in those younger; LDL-C, hypertension and diabetes were mainly associated with risk of stroke in those below age 80.
Conclusion: Lack of leisure-time physical activity is a potentially modifiable stroke risk factor and was more notable than hypertension, diabetes or dyslipidemia among those older than age 80. Improving activity may reduce the risk of stroke in this segment of the population.