Long-term BPV is an Independent Risk Factor for Renal Prognosis in Hypertensive Patients - a Post-hoc Analysis of the SPRINT Study

Abstract

Background: Long-term blood pressure variability (BPV) reflects fluctuations in BP over time, which may indicate instability in precise blood pressure control. We conducted a post hoc analysis of the data from the SPRINT (Systolic Blood Pressure Intervention Trial) to assess the effect and associated variables of BPV on the renal prognosis of patients with hypertension. Methods: Excluding patients with CKD, the systolic blood pressure (SBP) at the 1^st, 6^th, and 12^th follow-up months were employed to calculate the SBP coefficient of variation (CV) which represented BPV. Patients were divided into four groups based on the quartiles of BPV, namely Q1 to Q4. Results: Group Q4 patients had higher baseline SBP. Multiple regression identified age, sex, treatment, current smoker, SBP, diastolic blood pressure (DBP), renin-angiotensin-system inhibitors (RASi), β-receptor antagonists, calcium channel blockers (CCBs), and other medications use were factors associated with BPV. The survival analysis showed that group Q4 had significantly more renal outcome events, and BPV was independently associated with the risk of renal outcome events (HR = 1.38, 95% CI: 1.23 - 1.54, P < 0.001). There was a direct correlation between the BPV and risk of renal outcomes when BPV exceeded 0.037. In addition, the RASi preference group reported a significantly higher incidence of renal outcome events compared to the non-preference group (log-rank test χ² = 6.218, P = 0.013) and exhibited a tendency towards higher BPV. Conclusions: High BPV is an independent risk factor for renal outcome events in hypertensive aging patients. The preference of RASi use can increase renal outcome events, but is not related to the rise in BPV. These findings suggest that in elderly hypertensive patients with elevated BPV, the potential risks of RASi-associated renal outcomes may outweigh its established benefits, necessitating cautious consideration of alternative antihypertensive strategies.

Keywords: blood pressure; blood pressure variability; hypertension; renal insufficiency; renin angiotensin system.

Figure 1

Follow-up of 5849 cases of hypertension. (A) Enrollment flow chart for the analysis of 5849 cases of hypertension. (B) Systolic blood pressure, (C) Diastolic blood pressure and (D) eGFR levels during follow-up. Abbreviations: eGFR, estimated glomerular filtration rate; Q1 to Q4, lowest to highest quartile.

Figure 2

Effect of BPV on renal prognosis in hypertensive patients. (A) Survival curves for renal outcome events according to BPV quartiles. (B) Spline plots for risk of renal outcome events over the range of BPV. Curves represent hazard ratios (solid dark color line) and 95% CI (light color lines) based on restricted cubic splines analysis. (C) Survival curves for renal outcome events according to intensive treatment under BPV groups. (D) Forest plot for interaction effect between BPV and intensive treatment. Abbreviations: BPV, blood pressure variability; Q1 to Q4, lowest to highest quartile.

Figure 3

Renal outcome events survival curves according to antihypertensive drug types and association of BPV with antihypertensive drug types. (A) Renal outcome event survival curves according to the use of RASi. (B) Renal outcome event survival curves according to the use of β-receptor antagonists. (C) Renal outcome event survival curves according to the use of CCBs. (D) Survival curves for renal outcomes according to use of diuretics. (E) Comparison of BPV between medication preference and non-preference groups. CCBs, calcium channel blockers; RASi, renin-angiotensin-system inhibitors.