Pre-dialysis diastolic blood pressure and intradialytic hypotension in patients undergoing maintenance haemodialysis.

Abstract

Intradialytic hypotension is a clinically relevant complication in haemodialysis patients. Pre-dialysis diastolic blood pressure is routinely measured. However, the association between pre-dialysis diastolic blood pressure and intradialytic hypotension is not well understood. Patient-level (N = 545) and haemodialysis session-level (N = 3261) data were collected; the exposure variable was pre-dialysis diastolic blood pressure. The primary outcome of interest was the development of intradialytic hypotension, defined as any nadir < 100mmHg if the pre-dialysis systolic blood pressure was ≥ 160mmHg, or any nadir < 90mmHg if the pre-dialysis systolic blood pressure was < 160mmHg. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using mixed-effects logistic regression for the association between pre-dialysis diastolic blood pressure and intradialytic hypotension, after adjusting for potential confounders. Intradialytic hypotension occurred in 14.4% of the sessions. All sessions were divided into five categories according to pre-dialysis diastolic blood pressure. The adjusted ORs for intradialytic hypotension were 2.72 (95% CI 1.64-4.51), 1.07 (95% CI 0.68-1.66), 1.68 (95% CI 1.08-2.62), and 1.81 (95% CI 1.05-3.14) in sessions with pre-dialysis diastolic blood pressure of < 60mmHg, ≥ 60 to < 70mmHg, ≥ 80 to < 90mmHg, and ≥ 90mmHg, respectively, compared with the reference pre-dialysis diastolic blood pressure of ≥ 70 to < 80mmHg. Cubic spline analyses revealed a reverse J-shaped association between pre-dialysis diastolic blood pressure and intradialytic hypotension. Low and high pre-dialysis diastolic blood pressure levels were associated with intradialytic hypotension. This may help identify patients at a high risk of developing intradialytic hypotension.