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

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. 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. 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. 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.