OBJECTIVES: Invasive mold infections (IMI) are associated with considerable morbidity and mortality in immunocompromised hosts, with fatality rates approaching 100% when therapy is delayed. Among IMI, aspergillosis (IA) is far more common than mucormycosis (IM). As a result, IA-targeted empirical treatment with voriconazole is often initiated in patients with suspected pulmonary IMI, but this therapy overlooks IM. Recently, isavuconazole has been approved in Canada as a monotherapy for the treatment of both IA and IM. The objective of this study was to assess the economic impact of isavuconazole compared to voriconazole for the treatment of suspected pulmonary IMI in Canada.

METHODS: A decision tree was developed over a 5-year time horizon from the Canadian Ministry of Health (MoH) and societal perspectives. The target population were patients with suspected pulmonary IMI, among which IA and IM were estimated to account for 95% and 5%, respectively. Efficacy parameters, including the percentage of patients using a second-line treatment and the rate of all-cause mortality, were extracted from the isavuconazole trials (SECURE and VITAL). Costs included were those associated with treatment acquisition, hospitalization, management of adverse events and productivity loss. Deterministic and probabilistic sensitivity analyses (PSA) were also conducted.

RESULTS: Isavuconazole was associated with a gain of 0.146 QALY, compared to voriconazole for IMI. From a MoH perspective, isavuconazole and voriconazole were associated with total costs of $C48,479 and $C44,088, respectively (difference $C4,391), which resulted in an incremental cost-utility ratio of $C30,160/QALY. Results were similar from a societal perspective. PSA for isavuconazole showed that it remained a cost-effective strategy in 62% of simulations from a MoH perspective, relative to a willingness to pay threshold of $C50,000/QALY.

CONCLUSIONS: This economic evaluation demonstrates that, in comparison to voriconazole, isavuconazole is a cost-effective strategy for the treatment of patients suspected of having an IMI.