Systolic Blood Pressure and Outcomes in Stage 3–4 Chronic Kidney Disease Patients: Evidence from a Taiwanese Cohort

BACKGROUND: Systolic blood pressure (SBP) goal for chronic kidney disease (CKD) patients is ≤140mm Hg. However, the SBP target provides no suggested lower limit, and some studies indicate that a lower SBP target may be harmful. We aimed to investigate the J-shaped relationship between SBP and clinical outcomes in CKD patients and the factors that modify this relationship. METHODS: This prospective observational study enrolled 2,144 CKD stage 3-4 patients between November 2002 and May 2009 and followed them until July 2010 or death. Patients included were also enrolled within the Integrated CKD Care Program for Delaying Dialysis in a medical center and its branch hospital. Demographic, clinical, laboratory, and disease variables at baseline and end of observation were measured. RESULTS: In diabetic CKD patients, the hazard ratio (HR) at SBP 96-110mm Hg vs. 111-120mm Hg was 2.52 (95% confidence interval (CI) = 1.13-5.58) for cardiovascular outcomes and was 3.14 (95% CI = 1.16-8.49) for renal outcomes. In nondiabetic CKD patients, this J-shaped relationship was not seen. Heavy proteinuria was further found to modify the J-shaped relationship in diabetic CKD patients. The HR for renal outcomes at SBP 96-110mm Hg vs. 111-120mm Hg was 4.07 (95% CI = 1.18-13.99) in diabetic CKD patients with heavy proteinuria vs. 1.72 (95% CI = 0.13-22.5) in those without heavy proteinuria. CONCLUSIONS: Diabetic CKD patients have a J-shaped relationship between SBP and cardiovascular or renal outcomes, but nondiabetic CKD patients do not. The optimal SBP range might be narrower in the diabetic CKD patients.