Effect of serum sodium concentration and tolvaptan treatment on length of hospitalization in patients with heart failure.

PURPOSE: The effect of serum sodium concentration and tolvaptan treatment on length of stay (LOS) in patients hospitalized with heart failure (HF) was evaluated. METHODS: Data for this study were derived from a large, international, Phase III trial of patients hospitalized for HF. Two distinct post hoc analyses were performed, analyzing the association between serum sodium concentration and index hospitalization LOS in normonatremic patients and hyponatremic patients treated with placebo plus standard of care versus tolvaptan. Analysis of covariance models were constructed to adjust for potential variation in care delivery and adjusted for hyponatremia status or treatment. RESULTS: Patients with a baseline serum sodium concentration of <135 meq/L who received placebo had an adjusted mean LOS that was 3.06 days longer than did normonatremic patients (p < 0.001). More severely hyponatremic patients had an adjusted mean LOS 5.18 days longer than did normonatremic patients (p < 0.001). In an analysis of all hyponatremic patients, those receiving tolvaptan had an adjusted mean LOS that was 1.72 days shorter than patients receiving placebo, though this difference was not significant. In more severely hyponatremic patients (serum sodium concentration of <130 meq/L), patients treated with tolvaptan had an adjusted mean LOS 2.12 days shorter than those receiving placebo, but this difference was not significant. CONCLUSION: A secondary analysis of a large, international, Phase III trial of patients hospitalized for HF demonstrated that comorbid hyponatremia was associated with a significant increase in hospital LOS. Treatment of hyponatremia with tolvaptan was associated with reductions in LOS that were not significant.