Association of Blood Pressure With the Progression of CKD: Findings From KNOW-CKD Study

Rationale & objective: Optimal blood pressure (BP) control is a major therapeutic strategy in the management of chronic kidney disease (CKD). We studied the association between BP and adverse kidney outcomes within a diverse cohort of Koreans with CKD.

Study design: Prospective observational cohort study.

Setting & participants: 2,044 participants from the Korean Cohort Study for Outcomes in Patients With CKD (KNOW-CKD).

Exposures: Baseline and time-updated systolic BP (SBP) and diastolic BP (DBP).

Outcome: A composite kidney outcome of a≥50% decline in estimated glomerular filtration rate (eGFR) from the baseline value or incident kidney replacement therapy.

Analytical approach: Multivariate cause-specific hazards models and marginal structural models were fitted for baseline and time-updated BP, respectively.

Results: During 7,472 person-years of follow-up, the primary composite kidney outcome occurred in 473 participants (23.1%), an incidence rate of 63.3 per 1,000 patient-years. Compared with baseline SBP<120mm Hg, the hazard ratios (HRs) for 120-129, 130-139, and≥140mm Hg were 1.10 (95% CI, 0.83-1.44), 1.20 (95% CI, 0.93-1.59), and 1.43 (95% CI, 1.07-1.91), respectively. This association was more evident in the model with time-updated SBP, for which the corresponding HRs were 1.31 (95% CI, 0.98-1.75), 1.59 (95% CI, 1.16-2.16), and 2.29 (95% CI, 1.69-3.11), respectively. In the analyses of DBP, we observed that time-updated DBP but not baseline DBP was significantly associated with the composite kidney outcome. Compared to patients with SBP<120mm Hg, patients with higher SBP had steeper slopes of eGFR decline. In the model including both SBP and DBP, only SBP was significantly associated with the composite kidney outcome.

Limitations: Observational design, unmeasured confounders, and use of office BPs only.

Conclusions: In patients with CKD, higher SBP and DBP levels were associated with a higher risk of a composite kidney outcome reflecting CKD progression. SBP had a greater association with adverse kidney outcomes than DBP.