Intra-dialytic blood pressure variability is a greater predictor of cardiovascular events in hemodialysis patients

Abstract

Background

Short-term and long-term blood pressure variability (BPV) in hemodialysis (HD) population are risk factors of cardiovascular diseases (CVD) and all-cause mortality. There is no full consensus on the best BPV metric. We compared the prognostic role of intra-dialytic and visit-to-visit BPV metrics for CVD morbidity and all-cause mortality in HD patients.

Methods

A retrospective cohort of 120 patients on HD was followed up for 44 months. Systolic blood pressure (SBP) and baseline characteristics were collected for 3 months. We calculated intra-dialytic and visit-to-visit BPV metrics, including standard deviation (SD), coefficient of variation (CV), variability independent of the mean (VIM), average real variability (ARV) and residual. The primary outcomes were CVD events and all-cause mortality.

Results

In Cox regression analysis, both intra-dialytic and visit-to-visit BPV metrics were associated with increased CVD events (intra-dialytic CV: HR 1.70, 95% CI 1.28–2.27, p < 0.01; visit-to-visit CV: HR 1.55, 95% CI 1.12–2.16, p < 0.01), but not associated with increased all-cause mortality (intra-dialytic CV: HR 1.32, 95% CI 0.99–1.76, p = 0.06; visit-to-visit CV: HR 1.22, 95% CI 0.91–1.63, p = 0.18). Overall, intra-dialytic BPV showed greater prognostic ability than visit-to-visit BPV for both CVD event (AUC of intra-dialytic BPV and visit-to-visit BPV metrics respectively: SD 0.686, 0.606; CV 0.672, 0.425; VIM 0.677, 0.581; ARV 0.684, 0.618; residual 0.652, 0.586) and all-cause mortality (SD 0.671, 0.608; CV 0.662, 0.575; VIM 0.669, 0.581; ARV 0.529, 0.588; residual 0.651, 0.602).

Conclusion

Compared to visit-to-visit BPV, intra-dialytic BPV is a greater predictor of CVD event in HD patients. No obvious priority was found among various BPV metrics.