OBJECTIVES : The morbidity and mortality associated with influenza is substantial in people with high-risk conditions (HRC) for complications. Baloxavir marboxil (baloxavir) was previously found to be a cost-effective alternative to laninamivir in otherwise healthy adults in Japan. The aim of this study was to investigate the cost-effectiveness of baloxavir versus laninamivir in patients with HRC in Japan.

METHODS : A decision tree was developed to estimate costs and health gains associated with the use of baloxavir compared to laninamivir over a lifetime horizon. The study population was stratified in three categories: non-elderly adults with HRC, elderly without other HRC, and elderly with other HRC. The cost-effectiveness was assessed from a public health care payer’s perspective. Numbers of symptomatic days, probabilities of complications and probabilities of drug-related adverse events (DRAEs) were obtained from a clinical trial and network meta-analysis. Costs of influenza management and DRAEs were obtained from the JammNet claims database. Health state utilities were driven by influenza symptoms, DRAEs and complications, with inputs informed by EQ-5D-5L data from a clinical trial of baloxavir and literature. Deterministic and probabilistic sensitivity analyses (DSA/PSA) were performed.

RESULTS : The baloxavir strategy was associated with higher costs (+¥144) and higher QALYs (+0.001, +0.002 and +0.004 in adults with HRC, elderly without HRC and elderly with HRC respectively). The overall incremental cost/QALY gained for baloxavir versus laninamivir was ¥68,617, which was below the willingness-to-pay threshold of ¥5,000,000/QALY. The most influential factors of the model results were probability of pneumonia and bronchitis based on the results of DSA. The PSA showed 94% probability that baloxavir is cost-effective versus laninamivir in total HR population.

CONCLUSIONS : This study suggests that influenza treatment with baloxavir is cost-effective compared to laninamivir in the adult population with HRC in Japan.