Age-Specific Rural-Urban Disparities in the Incidence of Ischemic Stroke in the Netherlands

Abstract

Background and Objectives Multiple studies found a higher ischemic stroke incidence in rural areas compared with urbanized areas, often explained by a low socioeconomic status (SES). However, this has rarely been investigated specifically in younger adults. We aimed to investigate the age-specific (15–49 years vs 50+ years) incidence of ischemic stroke in rural and urbanized municipalities within the Netherlands. Methods Patients with a first-ever ischemic stroke (15 years or older) between 1998 and 2018 were included in this registry-based study through linkage of Dutch national hospital administrative registries. Ischemic stroke was defined through ICD-9 and ICD-10 codes. The urbanization grade of the municipality was defined by the address density in 5 subgroups (from most urban ≥2,500 addresses per km2 to rural <500 addresses per km2). The urbanization grade-specific incidence rate per 100,000 person-years, standardized for age and sex, and incidence rate ratios (IRRs) were calculated. In addition, we performed stratified analyses for young age groups (15–39 and 40–49 years) and neighborhood SES (nSES), which was calculated using welfare, level of education, and recent labor participation. Results In total, 23,720 patients aged 15–49 years (median age 44.7 years [interquartile range (IQR) 40.6–48.8], 51.6% women) and 369,107 patients aged older than 50 years (median age 76.7 years [IQR 68.8–84.7], 50.8% women) were included. Patients aged 15–49 years living in rural areas showed a 5% higher risk of ischemic stroke (IRR 1.05 [99% CI 0.98–1.13]) compared with patients in urbanized areas, whereas for persons aged 50 years and older, this risk was decreased by 3% (IRR 0.97 [99% CI 0.95–0.98]). For patients aged 15–39 years, this risk was 20% higher (IRR 1.20 [99% CI 1.05–1.37]), and for patients aged 40–49 years, the risk did not differ (IRR 1.01 [99% CI 0.93–1.09]). The rural-urban disparities in all age groups remained similar when stratified for nSES. Discussion The incidence of ischemic stroke is higher among persons aged 15–49 years living in rural areas compared with urban areas, which was driven by a risk-increase in patients 15–39 years. This was reversed among persons aged 50 years and older. Our findings were not fully explained by differences in nSES. This suggests that different age-specific predictors might play a role in rural-urban disparities in ischemic stroke incidence.