Association of blood pressure and renal outcome in patients with chronic kidney disease; a post hoc analysis of FROM-J study

Abstract

It is well-known that hypertension exacerbates chronic kidney disease (CKD) progression, however, the optimal target blood pressure (BP) level in patients with CKD remains unclear. This study aimed to assess the optimal BP level for preventing CKD progression. The risk of renal outcome among different BP categories at baseline as well as 1 year after, were evaluated using individual CKD patient data aged between 40 and 74 years from FROM-J [Frontier of Renal Outcome Modifications in Japan] study. The renal outcome was defined as ≥ 40% reduction in estimated glomerular filtration rate to < 60 mL/min/1.73 m², or a diagnosis of end stage renal disease. Regarding baseline BP, the group of systolic BP (SBP) 120-129 mmHg had the lowest risk of the renal outcome, which increased more than 60% in SBP ≥ 130 mmHg group. A significant increase in the renal outcome was found only in the group of diastolic BP ≥ 90 mmHg. The group of BP < 130/80 mmHg had a benefit for lowering the risk regardless of the presence of proteinuria, and it significantly reduced the risk in patients with proteinuria. Achieving SBP level < 130 mmHg after one year resulted in a 42% risk reduction in patients with SBP level ≥ 130 mmHg at baseline. Targeting SBP level < 130 mmHg would be associated with the preferable renal outcome.Clinical Trial Registration-URL: https://www.umin.ac.jp/ctr/ . Unique identifier: UMIN000001159 (16/05/2008).

Figure 1

Kaplan–Meier analyses for renal outcome based on baseline SBP and DBP levels (A,B), and stratified by the presence or absence of baseline proteinuria (C,D). (A) Analyses of baseline SBP levels (6 groups); The SBP 120–129 mmHg group had the lowest risk of the renal outcome. (B) Analyses of baseline DBP levels (4 groups); the risk of renal outcome significantly increased only in the DBP ≥ 90 mmHg group compared to the DBP 70–79 mmHg group. *p < 0.05 vs SBP 120–129 mmHg (Log-rank), **p < 0.001 vs SBP 120–129 mmHg (Log-rank), ^†p < 0.05 vs DBP 70–79 mmHg (Log-rank). (C) Patients with proteinuria; proteinuria was defined as ≥  ± by dipstick test. The baseline BP < 130/80 mmHg group significantly reduced the risk of the renal outcome compared to the other. (D) Patients without proteinuria; No significant difference was found in renal outcome. SBP systolic blood pressure, DBP diastolic blood pressure, BP blood pressure, HR hazard ratio. Hazard ratios have been adjusted for nine prespecified baseline factors (age, sex, body mass index, smoking, presence of diabetes mellitus, presence of dyslipidemia, presence of hyperuricemia, use of anti-hypertensive medication and intervention arm).

Figure 2

Kaplan–Meier analyses of renal outcome based on management of BP levels after 1 year (n = 2044). Patients were divided into 4 groups according to management of SBP and DBP levels, respectively, at baseline and after 1 year. (A) Analyses of SBP level at baseline and after 1 year; the failure and the late achiever had significant higher risk of renal outcome compared to the achiever. (B) Analyses of DBP level at baseline and after 1 year; no significant difference was found among groups. *p < 0.05 vs achiever (Log-rank), **p < 0.001 vs achiever (Log-rank). BP blood pressure.

Figure 3

Kaplan–Meier analyses of renal outcome between the group A and B, stratified by baseline BP levels in patients with eGFR < 60 ml/min/1.73 m² (A,B) and ≥ 60 ml/min/1.73 m² (C,D). The difference in the effect on renal outcome between the group A and B was compared in the patients with eGFR < 60 ml/min/1.73 m² (A,B). Patients in group A (standard intervention) were simply instructed to follow the medical guidelines of the Japanese Society of Nephrology. On the other hand, patients in group B (advanced intervention) received an educational session by a dietitian and a letter regarding ideal lifestyle for CKD and were notified 1 week prior to the consultation. (A) Baseline SBP < 130 mmHg and DBP < 80 mmHg; No significant difference was observed. (B) The group B significantly reduced renal outcome compared to the group A. No significant difference was observed in patients with eGFR ≥ 60 ml/min/1.73 m² (C,D). BP blood pressure, SBP systolic blood pressure, DBP diastolic blood pressure, eGFR estimated glomerular filtration rate.

Figure 4

Flow chart of patients. CKD chronic kidney disease, FROM-J Frontier of Renal Outcome Modifications in Japan, eGFR estimated glomerular filtration rate.