Combined pre-dialysis systolic blood pressure and pulse rate assessment for all-cause and cardiovascular mortalities: A nationwide cohort study on patients undergoing haemodialysis

Abstract

Background and Aims The prognostic utility of the combined assessment of pre-haemodialysis systolic blood pressure (SBP) and pulse rate (PR) compared with their individual assessment is unclear. This study aimed to determine whether the combined assessment could enhance the prognostic utility in patients on haemodialysis. Methods This nationwide cohort study involved patients undergoing maintenance haemodialysis using the Japanese Renal Data Registry database. Exposure was defined as a combination of SBP and PR. Forty-eight levels of exposure groups were created: SBP (six levels; <100, 100-<120, 120-<140, 140-<160 [reference], 160-<180, and ≥180 mmHg) and PR (eight levels; <50, 50-<60, 60-<70 [reference], 70-<80, 80-<90, 90-<100, 100-<110, and ≥110 per minute). The primary and secondary outcomes were one-year all-cause and cardiovascular mortalities, respectively. Multivariate Cox proportional hazards models were used, and multiplicative interactions were assessed to determine the superiority of the combined model over the individual models. Additive interactions were assessed using relative excess risk due to interactions (RERI). Results The combined model explained mortality and cardiac mortality better than the individual SBP and PR models (P<0.001 and P<0.002, respectively). A lower SBP was associated with a higher risk of all-cause mortality regardless of the PR. Most categories of lower SBP or higher PR vs. the 120-<140 mmHg and 70-<80/min category had positive RERIs. Similar findings were also observed for cardiac mortality. Conclusions The combined assessment of pre-dialysis SBP and PR may help in the simple stratification of patients with excess risks that cannot be identified by individual SBP or PR assessment.