Blood Pressure and Kidney Disease Progression in Advanced Chronic Kidney Disease: Findings from the CRIC and KNOW-CKD Studies

Background: Blood pressure (BP) control is important in the management of chronic kidney disease (CKD). However, in patients with advanced CKD, the benefits of BP control in delaying the progression of CKD remain uncertain. Methods: We analyzed 2,939 participants with CKD G3b to G5 (estimated glomerular filtration rate [eGFR] <45 ml/min/1.73m 2 ) without kidney replacement therapy from the Chronic Renal Insufficiency Cohort (CRIC) study and the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD) (Phase I). The main predictors were baseline and time-updated systolic BP (SBP) and diastolic BP (DBP). The primary outcome was a composite kidney outcome of ≥50% decline in eGFR from baseline measurement or the initiation of kidney replacement therapy. In the analyses, multivariate cause-specific hazards models and marginal structural models were fitted for baseline and time-updated BPs, respectively. Results: During 17,755 person-years of follow-up (median, 4.7 years), the composite outcome occurred 1,627 (55%) participants. Compared with baseline SBP <120 mmHg, the HRs (95% CIs) for 120–129, 130–139, and ≥140 mmHg were 1.33 (1.15–1.54), 1.48 (1.27–1.72), and 1.82 (1.58–2.10), respectively. This association was more evident in analysis with time-updated SBP, where the corresponding HRs (95% CIs) were 1.29 (1.09–1.54), 1.75 (1.46–2.10), and 2.79 (2.36–3.29), respectively. Furthermore, the slopes of eGFR decline were -1.20 (-1.36 to -1.04), -1.77 (-1.97 to -1.57), -2.11 (-2.35 to -1.88), and -2.48 (-2.70 to -2.27) mL/min/1.73m 2 per year for respective baseline SBP categories. Additional analyses with DBP also showed similar results. Conclusion: In patients with advanced CKD, higher BP levels were associated with a higher risk of CKD progression.