OBJECTIVES

: To assess cost-effectiveness (CE) of isavuconazole for the treatment of possible invasive aspergillosis (IA) in Czech adult patients when, at the point of treatment initiation, a differential diagnosis between IA and mucormycosis has not been achieved. Isavuconazole was compared to the standard of care (SoC, i.e. voriconazole) which is ineffective against mucormycosis, and thus leads to increased mortality.

METHODS

: A decision tree model (DT) was created to assess CE. The DT modelled presence of either IA or mucormycosis. However, given the difficulties in achieving a prompt differential diagnosis, antifungal treatment must be initiated before pathogen information becomes available. The model projects quality-adjusted life-years (QALYs) and costs from healthcare payers’ perspective. Costs were based on list prices and reimbursement tariffs as of February 2018. Treatment efficacy, short-term mortality and adverse events data were derived from clinical trials. Results were extrapolated to a lifetime horizon using average life expectancy and quality of life relevant to the underlying health condition of patients treated for invasive mould disease (i.e. acute myeloid leukaemia). Costs and outcomes were discounted by 3%. One-way sensitivity analysis (OWSA) accompanied by scenario analysis (SA) were performed. Probabilistic sensitivity analysis (PSA; 1000 iterations) was performed using an implicit willingness-to-pay (WTP) threshold of €47,000/QALY.

RESULTS

: Over a lifetime horizon, isavuconazole yields additional 0.30 QALYs (7.80 vs. 7.50) at the additional total cost of €3059 (€18,664 vs. €15,605) compared with SoC, with the incremental cost-effectiveness ratio of €10,251 per QALY. PSA showed that probability of isavuconazole to be cost-effective is 75% at the WTP threshold. OWSA and SA confirmed the robustness of the base-case result while the most influential parameters were mortality and prevalence of mucormycosis.

CONCLUSIONS

: The model suggests that compared to voriconazole, isavuconazole may provide a benefit in quality-adjusted life-years and may be cost-effective using the Czech implicit willingness-to-pay threshold.