Dialysate Sodium Concentration and the Association with Interdialytic Weight Gain, Hospitalization, and Mortality

Abstract

SummaryBackground and objectives Recommendations to decrease the dialysate sodium (DNa) prescription demand analyses of patient outcomes. We analyzed morbidity and mortality at various levels of DNa, simultaneously accounting for interdialytic weight gain (IDWG) and for the mortality risk associated with lower predialysis serum sodium (SNa) levels.Design, setting, participants, & measurements We used multiply-adjusted linear mixed models to evaluate the magnitude of IDWG and Cox proportional hazards models to assess hospitalizations and deaths in 29,593 patients from the Dialysis Outcomes and Practice Patterns Study with baseline DNa and SNa as predictors, categorized according to lowest to highest levels.Results IDWG increased with higher DNa across all SNa categories, by 0.17% of body weight per 2 mEq/L higher DNa; however, higher DNa was not associated with higher mortality in a fully adjusted model (also adjusted for SNa; hazard ratio [HR]=0.98 per 2 mEq/L higher DNa, 95% confidence interval [CI] 0.95-1.02). Instead, higher DNa was associated with lower hospitalization risk (HR=0.97 per 2 mEq/L higher DNa, 95% CI 0.95-1.00, P=0.04). Additional adjustments for IDWG did not change these results. In sensitivity analyses restricted to study facilities, in which 90%-100% of patients have the same DNa (56%), the adjusted HR for mortality was 0.88 per 2 mEq/L higher DNa (95% CI 0.83-0.94). These analyses represented a pseudo-randomized experiment in which the association between DNa and mortality is unlikely to have been confounded by indication. ConclusionsIn the absence of randomized prospective studies, the benefit of reducing IDWG by decreasing DNa prescriptions should be carefully weighed against an increased risk for adverse outcomes.

Clinical Effects of Personalized Dialysate Sodium in Conventional, Quotidian, and Nocturnal Home Hemodialysis Patients: A Randomized Crossover Trial

“…DPNa + was superior to PPNa + in predicting IDWG%, predialysis diastolic, post-dialysis diastolic and mean arterial pressure (Table 3). This data is in contrast to a number of trials that suggest PPNa + to be more predictive [30,47,48]. Plasma Na + approaches Dial-Na + throughout hemodialysis, so intradialytic change in plasma Na + was predicted to be less than 3 mmol/L in our study, since Dial-Na + was randomized to be 3 mmol/L above (HIGHDialSOD) or below (LOWDialSOD) the SP.…”

Effect of Tenapanor on Interdialytic Weight Gain in Patients on Hemodialysis

“…This practice can lead to postdialysis hypernatremia that contributes to volume overload and increased BP (16). An increase of 0.17% of body weight for each additional 2 mmol/L dialysate sodium concentration has been reported (17). Reducing or individualizing dialysate sodium is now recommended as a means of improving control of sodium balance, volume, and BP in hypertensive patients on hemodialysis (16,18), and it has been shown to reduce IDWG and BP (19).…”

Dialysis Outcomes and Practice Patterns Study (DOPPS)

“…We have found that many facilities internationally use a single concentration of dialysate sodium, calcium, bicarbonate, or even potassium for nearly all patients, and that this single concentration varies between facilities (i.e., facilities choose one concentration or another). Recent DOPPS publications evaluating dialysate components, by IV analysis and other methods, have questioned the widespread belief that lower dialysate sodium levels are beneficial (47,48), and have raised the possibility that the commonly used dialysate potassium concentration of 2 mEq/L may raise the risk of sudden death compared with higher levels (41,49). Other analyses of dialysate composition are ongoing.…”