Reduced Glomerular Filtration Rate and Risk of Stroke: A Nationwide Cohort Study in South Korea

Aims: Although chronic kidney disease is recognized as an independent risk factor for cerebrovascular disease, its association with hemorrhagic and ischemic stroke remains controversial. Methods: We conducted a retrospective cohort study using the National Health Insurance Service-National Sample Cohort, which is representative of the Korean population. A total of 195,772 Koreans who were not diagnosed with stroke before 2009 were included in this study from 2009 to 2013. The eGFR was divided into six categories (≥ 90, 75–89, 60–74, 45–59, 30–44, ＜30 mL/min/1.73 m2). The Kaplan–Meier plot was illustrated to compare the incidence of stroke. Cox proportional hazard model was used to estimate the hazard ratio (HR) of eGFR for risk of ischemic and hemorrhagic stroke by sex. Results: During an average of 4.36 years of follow-up period, 2,236 and 668 people were diagnosed with newly ischemic and hemorrhagic stroke, respectively. Age-adjusted incidence rate for ischemic stroke among people with eGFR ＜45 mL/min/1.73 m2 was higher than those with eGFR ≥ 90 mL/min/1.73 m2, whereas that for hemorrhagic stroke among people with eGFR ≥ 90 mL/min/1.73 m2 was higher than those with eGFR ＜45 mL/min/1.73 m2. After adjusting for multiple covariates, the adjusted HR for ischemic stroke increased with decreasing eGFR in men (p for trend ＜0.001), but not in women (p for trend=0.48). On the other hand, there was no significant relationship between eGFR and risk of hemorrhagic stroke in both men and women. Conclusions: Reduced glomerular filtration rate less than 45 mL/min/1.73 m2 was associated with an increased risk of ischemic stroke, especially in men.