Nighttime Systolic Blood Pressure and Cardiovascular and All-Cause Mortality in Peritoneal Dialysis Patients: A Single-Center Prospective Cohort Study

Background/Objectives: The link between ambulatory-blood-pressure-derived measurements and survival outcomes among patients receiving peritoneal dialysis (PD) remains uncertain. This study sought to explore whether nighttime systolic blood pressure (SBP) obtained from 24-h ambulatory blood pressure monitoring (ABPM) is associated with cardiovascular (CV) and all-cause mortality in PD individuals. Methods: Between 1 January 2017 and 30 June 2021, this single-center sub-cohort study (derived from a prospective database of PD) enrolled 165 PD participants with a median follow-up of 47.4 months from the date of ABPM completion. Competing risk regression was applied to estimate the association between nighttime SBP and CV mortality, accounting for competing death events. Multivariable Cox proportional hazards regression was utilized to quantify nighttime SBP’s independent correlation with all-cause mortality. Results: Over the follow-up period, 48 patients (29.1%) died, with 28 (58.3%) cases attributed to CV causes. In the fully adjusted model, each 1 SD rise in nighttime SBP corresponded to a subdistribution hazard ratio (SHR) of 1.53 (95% confidence interval [CI], 1.05–2.21; p = 0.026) for CV mortality. In the Cox regression model, every 1 SD increase in nighttime SBP showed an independent association with a 42% excess risk of all-cause mortality (hazard ratio [HR] = 1.42, 95% CI, 1.04–1.93; p = 0.026). Quartile-stratified analyses indicated that participants within the uppermost nighttime SBP quartile exhibited higher mortality risk for both endpoints compared to those in the lowest quartile. Conclusions: Elevated nighttime SBP is associated with increased CV and all-cause mortality risk in PD patients.