Invasive aspergillosis: is treatment with "inexpensive" amphotericin B cost saving if "expensive" voriconazole is only used on demand?
BACKGROUND
Voriconazole for the treatment of invasive aspergillosis (IA) shows superior clinical outcome and tolerability compared to conventional amphotericin B. However, the latter is often used as initial treatment due to lower drug acquisition costs. Therefore we performed a cost-effectiveness analysis.


METHODS
A decision analytic model was designed to compare the cost-effectiveness of a regimen of voriconazole followed by conventional amphotericin B to a regimen of conventional amphotericin B followed by voriconazole. Patients initiated on treatment either completed initial therapy or switched to second line therapy due to toxicity or non-response. Probability of a switch was based on clinical trial data and local rates of renal toxicity. Resource use in the hospital was taken from the Global Comparative Aspergillosis (GCA) study. Costs were based on local drug acquisition costs, local cost estimates for hospitalisation and adjusted additional costs of amphotericin B-induced acute renal failure from the literature. Effectiveness was defined as survival at 12 weeks from the GCA study. An incremental cost-effectiveness ratio was estimated as the incremental cost per life saved comparing voriconazole to conventional amphotericin B.


RESULTS
Based on this model, initial therapy of IA with voriconazole reduced total costs when compared to initial therapy with conventional amphotericin B (CHF 37 878/patient vs CHF 49 861/patient) and resulted in better survival at 12 weeks, making it the dominant treatment in terms of incremental cost-effectiveness. Results were most sensitive to alternative assumptions of the incidence of acute renal failure, but cost savings were sustained for voriconazole over a wide range of values.


CONCLUSIONS
Considering that initial therapy with voriconazole is both cost-saving and results in better clinical outcomes, voriconazole is the dominant cost-effective option for initial therapy of IA, despite very low drug acquisition costs of conventional amphotericin B.
Garbino
Jorge
J
Infectious Disease Division, Unviersity Hospital Geneva, Geneva, Switzerland. jorge.garbino@hcuge.ch
Schnetzler
Gabriel
G
Roberts
Craig
C
D058186:Acute Kidney Injury / Q000191:economics* / Q000209:etiology; D000666:Amphotericin B / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D000935:Antifungal Agents / Q000191:economics / Q000627:therapeutic use*; D001228:Aspergillosis / Q000188:drug therapy* / Q000191:economics; D003362:Cost-Benefit Analysis; D003663:Decision Trees; D006801:Humans; D018803:Models, Economic; D011743:Pyrimidines / Q000191:economics* / Q000627:therapeutic use; D014230:Triazoles / Q000191:economics* / Q000627:therapeutic use; D065819:Voriconazole
D000935:Antifungal Agents; D011743:Pyrimidines; D014230:Triazoles; D000666:Amphotericin B; D065819:Voriconazole