Renal dysfunction increases the risk of ischemic and hemorrhagic stroke in the general population

Aims. The association between chronic kidney disease (CKD) and different subtypes of stroke is unclear, and previous studies have yielded conflicting results. We aimed to assess the impact of CKD on the risk of fatal or non-fatal ischemic and hemorrhagic stroke in both men and women. Methods. In 539,287 Swedish men and women, mainly undergoing health controls, with mean age 45 years, and no previous stroke or myocardial infarction, hazard ratios for stroke were calculated to assess the association between renal dysfunction and incidence of stroke. We estimated glomerular filtration rates (GFR) using the Mayo (GFR-Mayo) formula. Glomerular filtration rate 60-90, 30-60, and 15-30 mL per minute per 1.73 m(2) was defined as mildly, moderately, and severely decreased GFR, respectively. Results. There were 17,678 strokes, of which 72% were ischemic, 15% hemorrhagic, and 12% unspecified, during 12 years of follow-up. Hazard ratios (95% confidence intervals) for ischemic stroke were 1.09 (1.04-1.14) for mildly, 1.24 (1.10-1.39) for moderately, and 2.27 (1.63-3.17) for severely decreased GFR-Mayo. The corresponding figures for hemorrhagic stroke were 1.04 (0.93-1.15), 1.26 (0.96-1.64), and 2.31 (1.10-4.87). Ischemic stroke was related to all levels of decreased GFR-Mayo in both genders (P < 0.0003). Hemorrhagic stroke was only related to renal dysfunction among women; hazard ratios (95% confidence intervals) 1.38 (1.14-1.66) for mildly, 1.70 (1.13-2.57) for moderately, and 3.46 (1.09-10.9) for severely decreased GFR-Mayo. Conclusions. Already mildly decreased GFR-Mayo increases the risk of ischemic fatal or non-fatal stroke and severely decreased GFR-Mayo the risk of hemorrhagic stroke in the general population. In gender-specific analyses ischemic stroke was related to a decreased GFR-Mayo in both genders. Hemorrhagic stroke was only related to renal dysfunction among women.