Effect of dialytic phosphate reduction rate on mortality in maintenance hemodialysis patients: a matched case–control study

BACKGROUND: Phosphates, similar to urea, are small molecular substances that can be cleared during dialysis. Dialytic phosphate reduction rate (PRR) may, to some extent, be related to the relative amount of phosphates cleared during dialysis. However, few studies have evaluated the associations between PRR and mortality in maintenance hemodialysis (MHD) patients. In this study, we investigated the association between PRR and clinical outcomes in MHD patients. METHODS: This was a retrospective, matched case–control study. Data were collected from the Beijing Hemodialysis Quality Control and Improvement Center. Patients were divided into four groups according to PRR quartile. Age, sex, and diabetes were matched between the groups. The primary outcome was all-cause death, and the secondary outcome was cardiocerebrovascular death. RESULTS: The study cohort comprised 4063 patients who were divided into four groups according to the PRR quartile: group PRR(1) (< 48.35%), group PRR(2) (48.35% — 54.14%), group PRR(3) (54.14% — 59.14%), and group PRR(4) (≥ 59.14%). We enrolled 2172 patients (543 in each study group) by case–control matching. The all-cause death rates were as follows: group PRR(1): 22.5% (122/543), group PRR(2): 20.1% (109/543), group PRR(3): 19.3% (105/543), and group PRR(4): 19.3% (105/543). No significant differences in all-cause and cardiocerebrovascular death rates according to the Kaplan–Meier survival curves were found between the groups (log-rank test, P > 0.05). Multivariable Cox regression analysis revealed no significant differences in all-cause and cardiocerebrovascular death rates between the four groups (P = 0.461; adjusted hazard ratio, 0.99; 95% confidence interval, 0.97 – 1.02 versus P = 0.068; adjusted hazard ratio, 0.99; 95% confidence interval, 0.97 – 1.00, respectively). CONCLUSIONS: Dialytic PRR was not significantly associated with all-cause death and cardiocerebrovascular death in MHD patients.