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

Abstract

<b><i>Introduction:</i></b> 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. <b><i>Methods:</i></b> 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: &lt;31.25 mmol/L, <i>n</i> = 77; quartile 2: 31.25–32.31 mmol/L, <i>n</i> = 76; quartile 3: 32.31–33.6 mmol/L; <i>n</i> = 81; quartile 4: ≥33.6 mmol/L, <i>n</i> = 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. <b><i>Results:</i></b> 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 (<i>p</i> = 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. <b><i>Conclusions:</i></b> 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.