BACKGROUND: Tolvaptan is a vasopressin-receptor antagonist used as an alternative to fluid restriction (FR) for the treatment of dilutional hyponatremia (HN) in hospitalized patients with congestive heart failure (CHF). The efficacy of tolvaptan, compared to FR, as a treatment for HN was investigated in a prospective, multicenter, randomized, active-controlled, open-label trial (Gheorghiade et al., 2006).
OBJECTIVE: The objective of this cost-consequences study was to estimate the potential economic and health outcomes associated with tolvaptan, in comparison with FR.
METHODS: A decision-analytic model was developed from the perspective of a U.S. hospital system to estimate potential economic and health outcomes associated with tolvaptan compared to FR among hospitalized CHF patients with HN. The model considers patients with severe HN (serum sodium [SS] levels <125 mEq/L) and patients with mild-moderate FR-resistant HN (SS levels ≥125 mEq/L). Patients’ response to treatment with tolvaptan, based on response rates among all hyponatremic patients reported in Gheorghiade et al. (2006), was assumed not to change with HN severity. FR-resistant patients with mild-moderate HN were assumed not to respond to treatment with continued FR. The model assumes patients’ response to treatment influences their health consequences: hospital length of stay, probability of an intensive care unit admission, and probability of a 30-day allcause hospital readmission. Health consequences data were obtained from published studies that compared patients with and without HN (Shorr et al., 2011; Amin et al., 2013).
RESULTS: Among hospitalized CHF patients with severe HN, the model suggested that tolvaptan may yield a total cost-savings of $243 per patient when compared to FR. Among hospitalized CHF patients with mild-moderate FR-resistant HN, a total cost-savings of $608 per patient compared to continued FR. Tolvaptan drug costs were completely offset in both cases. Among hospitalized CHF patients with severe HN, the model suggested reductions of 7.2% and 4.6% in the numbers of ICU admissions and 30-day readmissions, respectively. The model suggested reductions of 14% and 9% in the numbers of ICU admissions and 30-day readmissions, respectively, among hospitalized CHF patients with mild-moderate FR-resistant HN.
CONCLUSIONS: As an effective treatment for HN among hospitalized CHF patients, tolvaptan, in comparison with FR, is expected to save hospitalization costs.
