Dependency of kidney function decline on intensive clinic blood pressure lowering in patients with high arterial stiffness: a post-hoc analysis of a randomized controlled trial

BACKGROUND Intensive blood pressure (BP) lowering increased acute kidney injury risk, despite cardiovascular benefits. We investigated the association between treatment-induced BP changes and kidney function decline, while accounting for arterial stiffness. METHODS This post‑hoc analysis included 266 patients with hypertension from a 20‑week double‑blind trial treated with calcium-channel blockers. Kidney dysfunction was defined as an estimated glomerular filtration rate (eGFR) <60 ml/min·1.73 m2 or a decrease ≥30% from baseline. Arterial stiffness was measured as brachial-ankle pulse wave velocity (baPWV). RESULTS At baseline, systolic/diastolic BP (mean±SD, 153.2±9.3/91.8±9.5 mmHg) was associated positively (r = 0.20 [95% CI, 0.09 to 0.32]/0.23 [95% CI, 0.11 to 0.34]) with serum creatinine (72.1±16.2 μmol/l), and inversely (r=-0.25 [95% CI, -0.36 to -0.14]/-0.16 [95% CI, -0.28 to -0.04]) with eGFR (91.6±13.8 ml/min·1.73 m2). The associations with clinic systolic BP were weakened with higher baPWV, being observed in tertiles 1 and 2 (r ≥ 0.30 or ≤-0.27), but not tertile 3. After 20 weeks treatment, the incidence of kidney dysfunction was 0%, 4.8%, and 6.4%, respectively, in tertiles 1, 2 and 3 of baPWV (odds ratio for tertile 3 versus tertile 1, 2.23 [95% CI, 0.84-5.95]). In longitudinal analysis, the least square mean change from baseline in eGFR was -3.7 ml/min·1.73 m2 (95% CI, -4.3 to 1.1) in patients within tertile 3 of both baseline baPWV and treatment-induced clinic systolic BP changes. CONCLUSIONS In patients with stiffer arteries, kidney function at baseline was not associated with higher BP, and its decline during follow-up was greater when clinic BP was intensively reduced.