Relationship between Dialysate Bicarbonate Concentration and All-Cause Mortality in Hemodialysis Patients

The optimal dialysate bicarbonate concentration (DBIC) for hemodialysis (HD) remains controversial. Herein, we analyzed the effect of dialysate bicarbonate levels on mortality in HD patients.

Patients undergoing maintenance HD were recruited from the HD unit of the Daping Hospital. Patients were categorized into quartiles according to their DBIC level (quartile 1: <31.25 mmol/L, n = 77; quartile 2: 31.25-32.31 mmol/L, n = 76; quartile 3: 32.31-33.6 mmol/L; n = 81; quartile 4: ≥33.6 mmol/L, n = 79). Demographic and clinical data were collected. Survival curves were estimated using the Kaplan-Meier method. A Cox proportional hazards regression model was used to estimate the association between DBIC and all-cause mortality.

We included 313 patients undergoing maintenance HD with a mean DBIC of 32.16 ± 1.59 mmol/L (range, 27.20-34.72 mmol/L). The patients in quartile 4 were more likely to have higher pre- and post-HD serum bicarbonate concentrations than those in other quartiles. The mortality rate was lowest in quartile 2 (10.53%). The survival time was significantly lower in the quartile 4 group than in the other quartiles (p = 0. 008, log-rank test). After full adjustment, the hazard ratio (per 3 mmol/L higher DBIC) for all-cause mortality was 4.29 (95% confidence interval, 2.11-8.47) in all patients, whereas no significant association was observed between DBIC and initial hospitalization.

Our data indicate that DBIC is positively associated with all-cause mortality. A DBIC concentration of 31-32 mmol/L may benefit patient outcomes. This study provides an evidence-based medical basis for optimal dialysis prescription in the future.