Does Lowering Dialysate Sodium Affect Patient Outcomes?

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Decreasing dialysate sodium prescription (DNa) reduces interdialytic weight gain (IDWG) but doesn’t lead to reduced mortality, according to a report in the Clinical Journal of the American Society of Nephrology.
The researchers analyzed data on nearly 26,000 patients from the Dialysis Outcomes and Practice Patterns Study (DOPPS). Morbidity and mortality were assessed at different levels of DNa, accounting for both IDWG and the risk of death associated with lower predialysis serum sodium levels.
At all levels of predialysis serum sodium, higher DNa was associated with increased IDWG. For each 2 mEq/L increase in DNa, there was a 0.17 percent increase in body weight. However, the final model—including adjustment for predialysis serum sodium—found no association between higher DNa and higher mortality.
This remained so even after further adjustment for IDWG. In facilities where at least 90 percent of patients had the same DNa (56 percent), the association with mortality was significant: adjusted hazard ratio 0.88 per 2 mEq/L increase. Because of the nature of the data, confounding by indication was considered unlikely.
Recent studies have suggested that reducing DNa may reduce IDWG. Before any such change in clinical practice is made, it’s important to assess the impact on patient outcomes.
The new analysis of DOPPS data does not support the theory that lowering DNa to reduce IDWG will translate to better patient outcomes. The researchers write, “In 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” [Hecking M, et al. Dialysate sodium concentration and the association with interdialytic weight gain, hospitalization, and mortality. Clin J Am Soc Nephrol 2012; 7:92–100].
March 2012 (Vol. 4, Number 3)