Novel risk score efficiently prevents tolvaptan-induced hypernatremic events in patients with heart failure

Background: It has been 7 years since tolvaptan was approved in Japan for the indication of heart failure in patients with volume overload; the drug can be used in patients with normonatremia. Hypernatremia was identified as a significant adverse event to be prevented. Methods and Results: We compiled and analyzed data from 3,349 patients over 5 years to identify patients at high risk of hypernatremia with tolvaptan treatment. The incidence of hypernatremia, defined as serum sodium ≥150 mEq/L, was 3.65%. Baseline serum sodium concentrations, serum potassium concentrations, blood urea nitrogen: creatinine ratio, initial tolvaptan dose, and age were identified as risk factors for hypernatremia. A hypernatremia risk score was developed using the odds ratios for these factors. The high-risk population was defined as patients with a risk score ≥17.80. Conclusions: To prevent the occurrence of hypernatremic events in patients taking tolvaptan, we recommend a very low starting dose (i.e., 3.75 mg/day) in patients identified as being at high risk of hypernatremia using our new scoring process.