Rural-Urban Differences in Stroke Risk Factors, Incidence, and Mortality in People With and Without Prior Stroke

Abstract

Background Rural residence is associated with stroke incidence and mortality, but little is known about potential rural/urban differences in ambulatory stroke care. Methods and Results We used the CANHEART (Cardiovascular Health in Ambulatory Care Research Team) cohort, created from linked administrative databases from the province of Ontario, Canada, and divided into primary (N=6 207 032) and secondary (N=75 823) prevention cohorts based on the absence or presence of prior stroke. We defined rural communities as those with a population size of ≤10 000 and within each of the primary and secondary prevention cohorts, compared cardiovascular risk factors and care between rural and urban areas. We then calculated sex-/age-standardized rates of stroke incidence and mortality per 1000 person-years between January 1, 2008 and December 31, 2012 and used cause-specific hazard models to compare outcomes in rural versus urban areas adjusting for age, sex, income, ethnicity, smoking, physical activity and comorbid conditions, and accounting for the competing risk of death in the model for the occurrence of stroke incidence. In the primary prevention cohort, rural residents were less likely than urban ones to be screened for diabetes mellitus (70.9% versus 81.3%) and hyperlipidemia (66.2% versus 78.4%) and less likely to achieve diabetes mellitus control (hemoglobin A1c ≤7% in 51.3% versus 54.3%; P<0.001 for all comparisons). In the secondary prevention cohort, the prevalence and treatment of risk factors were similar in rural and urban residents. After adjustment for sociodemographic and comorbid conditions, rural residence was associated with higher rates of stroke and all-cause mortality in both the primary prevention (adjusted hazard ratio [aHR] for stroke, 1.06; 95% CI, 1.04-1.09; aHR for mortality, 1.09; 95% CI, 1.08-1.10) and the secondary prevention cohort (aHR for stroke, 1.11; 95% CI, 1.02-1.19; aHR for mortality, 1.07; 95% CI, 1.03-1.11). Conclusions In this population-based study of over 6 million people with universal access to physician and hospital services, risk factors were more prevalent but less likely to be controlled in rural than in urban residents without prior stroke, whereas in those with prior stroke, risk factor prevalence and treatment were similar. Rural residence was associated with the rate of stroke and death even after adjustment for risk factors. Future efforts should focus not only on control of known vascular risk factors but also on addressing other determinants of health in rural communities.

Keywords: mortality; prevalence; primary prevention; secondary prevention; stroke.