COST EFFECTIVENESS ANALYSIS OF ANTIFUNGAL PROPHYLAXIS IN HEMATOPOIETIC STEM CELL TRANSPLANT RECIPIENTS

Purpose: To estimate the cost effectiveness of antifungal prophylaxis of two newer antifungal agents, itraconazole and voriconazole, compared to fluconazole for the prevention of invasive fungal infections (IFI) in allogeneic hematopoietic stem cell transplant recipients in the immediate post-transplant period.  

Method: A decision-analytic Markov model was developed to compare the clinical benefits and costs associated with 2 antifungal prophylaxis strategies. Itraconazole and voriconazole were compared to fluconazole. The base case analysis was consistent with the Panel Recommendations for a Reference Case, using the societal perspective.

Results are reported in 2008 US dollars, life years (LY), and quality-adjusted life years (QALY). The willingness-to-pay (WTP) threshold was $100,000/QALY. Sensitivity analyses included one-way analyses for each variable and probabilistic analyses (including cost effectiveness acceptability curves (CEAC)). Result: The incremental cost effectiveness ratios (ICER) were $77,121/LY and $111,500/QALY gained for itraconazole compared to fluconazole. For voriconazole compared to fluconazole, the ICER was $228,544/LY and $310,615/QALY gained. When both itraconazole and voriconazole were compared to fluconazole in the same model, voriconazole was both more expensive and less effective than itraconazole; thus, itraconazole had strong dominance over voriconazole. Model results were most sensitive to the probability of developing an IFI, as discovered in one-way sensitivity analyses. In the CEAC, probabilities of being the optimal strategy with a $100,000 per QALY WTP threshold were 0.34, 0.63 and 0.03 for fluconazole, itraconazole, and voriconazole, respectively. Although the base case analysis shows itraconazole as borderline cost effective at $111,500/QALY, probabilistic sensitivity analyses showed that the greatest net benefit was derived from itraconazole when the WTP threshold was less than $100,000/QALY.

Conclusion: This economic evaluation suggests that itraconazole is the most cost effective treatment option at a WTP threshold of $100,000/QALY. Although itraconazole appears more expensive at face value, its health benefits make it an attractive prophylaxis option. Unlike other studies that do not consider cost, in this evaluation, voriconazole was not found to be the optimal treatment option.