Cost-Effectiveness Analysis of Molnupiravir Versus Best Supportive Care for the Treatment of Outpatient COVID-19 in High-Risk Older Adults in Japan

Objectives This analysis aimed to evaluate the cost effectiveness of molnupiravir versus best supportive care for the treatment of older adult patients (aged ≥ 65 years) in Japan with mild to moderate COVID-19 who are at risk of disease progression leading to hospitalization, predominantly using input data derived from the Omicron era of the SARS-CoV2 pandemic. Methods A decision-analytic model was developed, comprising a decision-tree model for the acute COVID-19 phase (30 days), followed by a lifetime Markov model. Inputs used to parametrize the model were derived from a database study conducted in Japan and a published systematic literature review of real-world studies, and from ad-hoc literature searches and other research (for disease progression, cost, and utility estimates). This analysis modelled death averted due to COVID-19 hospitalization as an indirect effect of molnupiravir (through preventing hospitalization). Costs were expressed in 2022 Japanese yen (¥; JPY), from the perspective of payers (the base case) or society (in a scenario analysis). Costs and QALYs were discounted at 2% per year. Cost effectiveness of molnupiravir versus best supportive care was primarily compared to a willingness-to-pay (WTP) threshold of ¥5,000,000 per quality-adjusted life year (QALY) gained. Results Treatment with molnupiravir is associated with a QALY gain of 0.018 and an incremental cost of ¥81,472 over best supportive care and is cost effective (with an incremental cost-effectiveness ratio [ICER] of ¥4,638,477) versus best supportive care based on the predefined WTP threshold of ¥5,000,000 per QALY gained. Molnupiravir leads to a reduction in the proportion of patients who die due to COVID-19 hospitalization (0.09% with molnupiravir vs 0.29% with best supportive care). Molnupiravir is also associated with lower costs associated with COVID-19 hospitalizations compared with best supportive care (¥22,527 vs ¥27,472). In a deterministic sensitivity analysis, the top five most sensitive parameters were baseline hospitalization rate, mortality benefit of molnupiravir, mortality rate in general ward, discount rate, and mortality rate in intensive care unit. In a probabilistic sensitivity analysis, at the predefined WTP threshold of ¥5,000,000 per QALY gained, molnupiravir had an 80% probability of being cost effective versus best supportive care. Conclusions Molnupiravir is a cost-effective treatment option for the treatment of older adult outpatients (age ≥ 65 years) with symptomatic COVID-19 in Japan, relative to best supportive care.