Systolic blood pressure time in target range and acute kidney injury in patients with hypertension

Abstract Background Although the systolic blood pressure (SBP) time in target range (TTR) shows great potential in predicting clinical outcomes in hypertensive patients, its role in reducing the incidence of acute kidney injury (AKI) requires further validation. The aim of this study was to investigate the associations between SBP TTR and AKI events. Methods This is a post-hoc analysis of the Systolic Blood Pressure Intervention Trial (SPRINT). Participants aged 50 or older were randomly assigned to intensive (120 mm Hg) or standard (140 mm Hg) SBP treatment arms. SBP TTR was defined as 110–130 mm Hg for the intensive arm and 120–140 mm Hg for the standard arm over 3 months. The primary outcome was incident AKI. The secondary outcome was the severity of AKI, based on modified KDIGO criteria. Competing risk models were used to estimate the relationship between SBP TTR and AKI. Results Of 8985 eligible participants, 258 experienced AKI, resulting in an incidence rate of 7.62 (95% CI, 6.72–8.61) per 1,000 person-years. Each 1-SD increase in SBP TTR was associated with a 15% reduction in AKI risk (adjusted HR, 0.85; 95% CI, 0.75-0.97; P=0.012), particularly for severe AKI stages (HR, 0.71; 95% CI, 0.58-0.87; P0.001). Compared to participants with lower TTR (0 to 59%), those with higher TTR (59 to 100%) had a lower risk of AKI events (HR: 0.67, 95% CI: 0.51–0.88, P 0.001). Furthermore, after categorizing by treatment arm, HRs (95% CIs) comparing the standard/lower group against intensive/lower, standard/higher, and intensive/higher were 1.71 (1.23–2.38; P = 0.001), 0.67 (0.44–1.01; P = 0.057), and 1.15 (0.78–1.71; P = 0.470), respectively. Conclusions Maintaining a higher SBP TTR significantly reduces the risk of AKI in hypertensive patients, underscoring the importance of sustained blood pressure management.