Lowest Systolic Blood Pressure Is Associated with Stroke in Stages 3 to 4 Chronic Kidney Disease

Abstract

Hypertension is a risk factor for stroke in the general population, whereas in hemodialysis patients, higher systolic BP (SBP) may be protective. Therefore, this study evaluated the relationship between SBP and stroke in individuals with and without chronic kidney disease (CKD) to assess whether this altered relationship exists in earlier stages of CKD. A secondary evaluation of two community-based, longitudinal, limited-access data sets was performed: Atherosclerosis Risk in Communities and Cardiovascular Health Study. CKD was defined as estimated GFR <60 ml/min per 1.73 m². The primary study outcome was definite or probable incident stroke. We used Cox proportional hazards models to assess the relationship between CKD and stroke, focusing on the role of SBP. Among 20,358 individuals studied, 1549 (7.6%) had CKD. During a median duration of 111 mo, 1029 (5.1%) individuals had a stroke. CKD and elevated SBP both independently predicted incident stroke (hazard ratio [HR] 1.22 [95% confidence interval [CI]1.02 to 1.44] and HR 1.18 [95% CI 1.14 to 1.21] per 10-mmHg rise, respectively). Individuals with CKD had a J-shaped relationship with stroke outcomes such that those with SBP <120 mmHg were at significantly increased risk compared with individuals with CKD and SBP 120 to 129 mmHg (HR 2.51; 95% CI 1.30 to 4.87); risk increased for BP >130 mmHg in CKD. This J shape was not seen in individuals without CKD. CKD and elevated SBP are independent risk factors for incident stroke. In CKD, individuals with the lowest BP are at increased risk for stroke. This pattern is not seen in the general population.