Relationship between kidney damage and stroke types in Japanese patients

Kidney disease is a known risk factor for stroke. This study investigated the relationship between kidney damage and stroke types. A total of 525 incident stroke patients were registered and followed for 1 year. The prevalence of kidney damage [proteinuria and/or renal insufficiency (estimated glomerular filtration rate < 60 ml/min/1.73 m(2))] in incident stroke and its effects on 1-year prognosis were examined. Among all stroke patients, kidney damage and its component (proteinuria and renal insufficiency) were commonly observed (48.2, 25.5, and 33.9%, respectively). The prevalence of ischemic stroke was significantly higher in patients with kidney damage (75.9%) than in those without (58.9%). The most frequent type of stroke among all patients with kidney damage and renal insufficiency only was cardioembolic infarction. In contrast, in patients with proteinuria only and patients without kidney damage, the most frequent type was subcortical and subarachnoid hemorrhage, respectively. Multiple logistic regression analysis showed that kidney damage or the combination of its components were independently associated with 1-year death [odds ratio (OR) 3.04, 95% confidence interval (CI) 1.40-6.59, P = 0.005 for kidney damage, OR 2.82, 95% CI 1.05-7.58, P = 0.040 for proteinuria only, and OR 5.77, 95% CI 2.23-15.0, P < 0.001 for both proteinuria and renal insufficiency]. In addition, for 1-year outcomes, there were selective associations between ischemic stroke and proteinuria and between hemorrhagic stroke and renal insufficiency. This study shows that kidney damage is common in Japanese stroke patients, and proteinuria and renal insufficiency are differentially related to development and prognosis, depending stroke types.