Cost-effectiveness of tolvaptan for euvolemic or hypervolemic hyponatremia

Purpose: Tolvaptan is clinically effective in increasing serum sodium concentrations for patients with euvolemic or hypervolemic hyponatremia. Appropriate treatment of hyponatremia may reduce the risk of death, hospital resource utilization, and economic burden. The aim of this study was to estimate the cost-effectiveness of tolvaptan treatment in patients who need to be hospitalized for treatment and monitoring of euvolemic or hypervolemic hyponatremia. Methods: A decision-analytic model was constructed to assess the clinical and economic impact of tolvaptan compared with placebo during a 1-month treatment period. The probabilities, utility weights, resource utilization, and costs in the model were derived from clinical trials, survey research, and the Korean National Health Insurance database. Cost analysis was performed from the perspective of the South Korean health care setting in 2012 Korean won (KRW). The model outcome was the incremental cost per quality-adjusted life-year gained. In addition, subgroup analysis was performed to identify the cost-effectiveness in case of tolvaptan treatment only for patients with marked hyponatremia. Deterministic and probabilistic sensitivity analyses were performed on key model parameters and assumptions. Findings: The total cost per patient was KRW 1,826,771 for tolvaptan treatment and KRW 2,281,926 for placebo. The quality-adjusted life-years for treatment with and without tolvaptan were 0.0481 and 0.0446, respectively. The base-case analysis revealed that tolvaptan was a more effective and less expensive strategy compared with placebo. In the subgroup analysis, this trend was more apparent in case of tolvaptan treatment only for patients with marked hyponatremia. The robustness of the results was confirmed by using deterministic and probabilistic sensitivity analyses. Implications: This cost-effectiveness analysis found that the use of tolvaptan was less expensive and more effective than treatment without tolvaptan in patients with euvolemic or hypervolemic hyponatremia.