Cost Effectiveness of Nail Fungus Confirmatory Test Treatment-Specific

Recommendations for universal confirmatory testing of toe nail fungus before systemic therapy should be replaced with therapy-specific recommendations, according to a study published Dec. 23, 2015 in JAMA Dermatology. The cost effectiveness of testing, the authors say, should be reconsidered in light of new drug pricing.

The new study found that empirical treatment with terbinafine for all patients with suspected onychomycosis is more cost-effective than confirmatory testing across all prevalence of disease, with "minimal" effect on patient safety. However, confirmatory testing before treatment with the new drug efinaconazole, is associated with cost savings, given the drug's high price tag.

Standard confirmatory testing was established in international guidelines based on cost-effectiveness studies from the 1990s. But since that time, the cost of treatment has changed dramatically. A full 12-week course of terbinafine dropped in cost from $547 in 1999 to $10 today, the authors say, while the novel topical solution efinaconazole, 10%, costs $2,307 for full treatment of one nail.

The researchers evaluated three approaches to onychomycosis evaluation before treatment with oral terbinafine or efinaconazole, 10%: empirical therapy without confirmatory testing; pretreatment confirmatory testing with potassium hydroxide (KOH) stain followed by periodic acid–Schiff (PAS) evaluation if KOH testing is negative; and pretreatment testing with PAS. Cost analyses were modeled for prevalences of 30 percent, 60 percent, 75 percent, and 90 percent. National reimbursement values were used to establish costs for KOH stain prep in the office ($6), PAS test ($148), and liver enzyme monitoring (aspartate aminotransferase, $21 and alanine aminotransferase, $22).

"Confirmatory testing for onychomycosis still has a place in clinical care. The emergence of efinaconazole, 10%, as a novel and expensive agent for the treatment of onychomycosis reinforces the value of confirmatory testing in an era of cost-containment."

—Anar Mikailov, M.D.

The study found that the cost for immediate treatment with terbinafine was lower than the cost for either of the testing strategies across all disease prevalences. At a disease prevalence of 75%, per-patient cost savings of empirical terbinafine therapy without confirmatory testing was $47, compared with the KOH screening model and $135 compared with PAS testing. In contrast, testing before treatment with efinaconazole, 10%, was associated with cost savings across all disease prevalence, with higher savings at a lower prevalence. At a disease prevalence of 75 percent, the savings of testing versus empirical therapy was $272 per nail with the KOH screening algorithm and $406 of savings per nail treated with the PAS algorithm.

"Although adverse events from inappropriate treatment with terbinafine for patients without onychomycosis is a concern, our analysis demonstrates that current testing paradigms create a substantial cost burden and require between $9.62 million and $233.89 million in testing costs to avoid one case of clinically apparent liver injury," write the authors led by Anar Mikailov, M.D., from Brigham and Women's Hospital in Boston, Mass. "Confirmatory testing for onychomycosis still has a place in clinical care. The emergence of efinaconazole, 10%, as a novel and expensive agent for the treatment of onychomycosis reinforces the value of confirmatory testing in an era of cost-containment."

Takeaway: The cost-effectiveness of confirmatory testing before initiation of treatment for onychomycosis is largely driven by drug costs and treatmentspecific recommendations should be followed for confirmatory testing.