Association of blood pressure with cardiovascular outcome and mortality: results from the KNOW-CKD study

Background Optimal blood pressure (BP) control is a major therapeutic strategy to reduce adverse cardiovascular events (CVEs) and mortality in patients with chronic kidney disease (CKD). We studied the association of BP with adverse cardiovascular outcome and all-cause death in patients with CKD. Methods Among 2238 participants from the KoreaN cohort study for Outcome in patients With CKD (KNOW-CKD), 2226 patients with baseline BP measurements were enrolled. The main predictor was systolic BP (SBP) categorized by five levels: <110, 110-119, 120-129, 130-139 and >= 140 mmHg. The primary endpoint was a composite outcome of all-cause death or incident CVEs. We primarily used marginal structural models (MSMs) using averaged and the most recent time-updated SBPs. Results During the follow-up of 10 233.79 person-years (median 4.60 years), the primary composite outcome occurred in 240 (10.8%) participants, with a corresponding incidence rate of 23.5 [95% confidence interval (CI) 20.7-26.6]/1000 patient-years. MSMs with averaged SBP showed a U-shaped relationship with the primary outcome. Compared with time-updated SBP of 110-119 mmHg, hazard ratios (95% CI) for <110, 120-129, 130-139 and >= 140 mmHg were 2.47 (1.48-4.11), 1.29 (0.80-2.08), 2.15 (1.26-3.69) and 2.19 (1.19-4.01), respectively. MSMs with the most recent SBP also showed similar findings. Conclusions In Korean patients with CKD, there was a U-shaped association of SBP with the risk of adverse clinical outcomes. Our findings highlight the importance of BP control and suggest a potential hazard of SBP <110 mmHg.