Cost-effectiveness of Baloxavir Marboxil compared with Laninamivir for the treatment of influenza in patients at high risk for complications in Japan.

Objective: Baloxavir marboxil (baloxavir) is a single-dose antiviral which was previously found to be a cost-effective alternative to laninamivir in otherwise healthy adults in Japan. This study aimed at investigating the cost-effectiveness of baloxavir versus laninamivir in patients with influenza at high risk for complications.Methods: A decision tree was utilized to estimate costs and health gains associated with the use of antivirals. The lifetime horizon was applied to capture the long-term impact of influenza complications, other events with associated costs and health outcomes were accounted for one influenza season. The study population was stratified into three categories: adolescents and non-elderly adults with high-risk conditions (HRC), elderly without other HRC, and elderly with other HRC. The cost-effectiveness was assessed from a public health care payer's perspective. The duration of influenza symptoms, probabilities of complications and probabilities of adverse events were obtained from a clinical trial and network meta-analysis. The costs of influenza and adverse events management were derived from the JammNet claims database. Utility values were informed by clinical trial data and literature. Sensitivity analyses were also performed.Results: The baloxavir strategy was associated with higher costs (+¥144) and higher quality-adjusted life-years (QALYs) in adults with HRC, elderly without HRC and elderly with HRC (+0.00078, +0.00183 and +0.00350 respectively). The overall incremental cost/QALY for baloxavir versus laninamivir was ¥68,855, which was below the willingness-to-pay threshold of ¥5 million/QALY gained. Key drivers of the model results were the probability of pneumonia and bronchitis. The probability of baloxavir being cost-effective was 72%.Conclusions: This study suggests that influenza treatment with baloxavir is cost-effective compared with laninamivir in the adult high-risk population in Japan.