Background: The difference in serum phosphate concentration pre- and post-dialysis values (ΔP) reflects phosphate removal during a hemodialysis session, which may be related to clinical outcomes in maintenance hemodialysis (MHD) patients. However, few studies have evaluated the associations between phosphate removal and mortality in MHD patients. In this study, we investigated the association between phosphate removal 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 ΔP 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 ΔP quartile: group ΔP1 (ΔP < 0.77 mmol/L), group ΔP2 (ΔP 0.77 – 0.95 mmol/L), group ΔP3 (ΔP 0.95 – 1.15 mmol/L), and group ΔP4 (ΔP ≥ 1.15 mmol/L). We enrolled 2512 patients (628 in each study group) by case–control matching. The all-cause death rates were as follows: group ΔP1: 21.2% (133/628), group ΔP2: 19.4% (122/628), group ΔP3: 19.6% (123/628), and ΔP4: (15.3% (96/628). 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 = 0.242; adjusted hazard ratio, 0.46; 95% confidence interval, 0.13 – 1.69 versus P = 0.670, adjusted hazard ratio, 0.69; 95% confidence interval, 0.12–3.87, respectively).
Conclusions: Dialytic serum phosphate removal was not significantly associated with all-cause death and cardiocerebrovascular death in MHD patients.