Pharmacoeconomic analysis of oral antifungal therapies used to treat dermatophyte onychomycosis of the toenails. A US analysis.

Abstract

Until a few years ago, griseofulvin and ketoconazole were the only 2 oral agents available for the treatment of dermatophyte onychomycosis of the toenails. With the availability of the newer antifungal agents, such as itraconazole, terbinafine and fluconazole, the armamentarium of drugs available to treat onychomycosis has expanded. The objective of this study was to determine the relative cost effectiveness of the most commonly used oral antifungal agents in the US for the treatment of dermatophyte onychomycosis of the toenails from the perspective of a third-party payer. The time horizon was 3 years. A 5-step approach was used in this pharmacoeconomic analysis. First, the purpose of the study, the comparator drugs and their dosage regimens were defined. In step II, the medical practice and resource-consumption patterns associated with the treatment of onychomycosis were identified. In step III, a meta-analysis was performed on all studies meeting prespecified criteria, and the mycological cure rates of the comparator drugs were determined. In step IV, the treatment algorithm for the management of onychomycosis was constructed for each drug. The cost-of-regimen analysis for each comparator incorporated the drug acquisition cost, medical-management cost and cost of managing adverse drug reactions. The expected cost per patient, number of symptom-free days (SFDs), cost per SFD and the relative cost effectiveness for the comparator drugs were calculated. In step V, a sensitivity analysis was performed. The drug comparators for this study were griseofulvin, itraconazole (continuous and pulse), terbinafine and fluconazole. The mycological cure rates [mean +/- standard error (SE)] from the meta-analysis were griseofulvin 24.5 +/- 6.7%, itraconazole (continuous) 66.4 +/- 6.1%, itraconazole (pulse) 76 +/- 9.3%, terbinafine 74 +/- 7% and fluconazole 59%. The cost per mycological cure was griseofulvin $US8089, itraconazole (continuous) $US1877, itraconazole (pulse) $US991, terbinafine $US1125 and fluconazole $US1506. The corresponding cost per SFD was griseofulvin $US7.05, itraconazole (continuous) $US2.18, itraconazole (pulse) $US1.26, terbinafine $US1.28 and fluconazole $US2.12. The resulting ratios of cost per SFD relative to itraconazole (pulse) [1.00] were terbinafine 1.02, itraconazole (continuous) 1:73, fluconazole 1.69 and griseofulvin 5.62. In conclusion, in this analysis, itraconazole (pulse) and terbinafine were the most cost-effective therapies for dermatophyte onychomycosis of the toenails, both being substantially more cost effective than griseofulvin.