ABSTRACT
OBJECTIVE: To evaluate clinical and economic outcomes associated with the use of isavuconazole as antifungal prophylaxis in high-risk immunocompromised patients. PATIENTS/METHODS: Retrospective, single-centre cohort study of patients who received isavuconazole prophylaxis. Outcomes assessed included breakthrough IFI, early discontinuation of isavuconazole for any reason and antifungal prophylaxis prescribed at discharge. The impact on inpatient drug expenditure was evaluated using current isavuconazole and posaconazole drug costs per observed isavuconazole days of therapy (DOT) during the study period. RESULTS: One hundred thirty-eight courses of isavuconazole prophylaxis were administered to 98 inpatients (2193 DOT). Relapsed/refractory acute myelogenous leukaemia was the indication for prophylaxis in over half (59.4%) of patients. Breakthrough IFI occurred in 8 (5.8%) courses. Suspected drug-related toxicities led to early discontinuation in 6 (4.3%) courses (five hepatotoxicity, one drug rash). At discharge, 24 (17.4%) courses lacked insurance coverage for isavuconazole. The formulary switch to isavuconazole prophylaxis resulted in an estimated mean drug cost savings of $128.25 per DOT relative to estimated posaconazole costs (P < 0.001). CONCLUSION: Isavuconazole may be an option for antifungal prophylaxis in high-risk immunocompromised adults and has the potential to produce significant inpatient drug cost savings. Further studies are needed to confirm the clinical efficacy and cost-effectiveness of isavuconazole in this role.