Person:

Mikailov, Anar

In Reply We thank Wang et al and Lipner and Scher for their interest in our study and agree with both groups about other potential consequences of terbinafine use.1 Our analysis of the adverse effects of terbinafine included only hepatic manifestations, given the US Food and Drug Administration and package insert recommendations to check transaminases prior to initiation of therapy and the availability of reliable incidence statistics from the National Library of Medicine LiverTox database. The other adverse effects mentioned by Wang et al and Lipner and Scher are certainly important; incidence statistics are not available for those adverse events, however, limiting our ability to perform a similar analysis. Nevertheless, we emphasize shared decision making with patients before prescribing systemic medications with the potential for idiosyncratic adverse drug reactions.

Importance Onychomycosis is the most common disease of the nail in adults. International guidelines urge health care professionals to perform confirmatory diagnostic testing before initiating systemic therapy. This approach was determined to be cost-effective in studies from the late 1990s but has not been evaluated more recently. The effect of testing on the costs of efinaconazole, 10%, topical solution treatment is unknown.

Objective To evaluate the cost and potential harm associated with 3 approaches to onychomycosis evaluation before treatment with oral terbinafine or efinaconazole, 10%.

Design, Setting, and Participants A decision analysis that compared the costs of 3 onychomycosis management algorithms based on recently published data of test statistics, disease prevalence, and relevant costs: (1) empirical therapy without confirmatory testing, (2) pretreatment confirmatory testing with potassium hydroxide (KOH) stain followed by periodic acid–Schiff (PAS) evaluation if KOH testing is negative, and (3) pretreatment testing with PAS. There was no direct patient evaluation. Selection of included studies was based on outcome variables and the quality of study design. The study was conducted from April 1, 2014, to September 1, 2015.

Main Outcomes and Measures Primary outcomes included direct cost of onychomycosis testing and therapy and cost to avoid harm when treating patients with oral terbinafine.

Results 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. The cost of testing necessary to prevent a single case of clinically relevant liver toxic effects related to terbinafine at a prevalence of 75% was between $18.2 million and $43.7 million for KOH screening and between $37.6 million and $90.2 million for PAS testing. At a prevalence of 75%, KOH screening and PAS testing before treatment with efinaconazole, 10%, saved $272 and $406 per patient per nail, respectively.

Conclusions and Relevance These results show that empirical treatment with terbinafine for patients with suspected onychomycosis is more cost-effective than confirmatory testing across all prevalence of disease, with minimal effect on patient safety. In contrast, confirmatory testing before treatment with efinaconazole, 10%, is associated with reduced costs. Blanket recommendations for confirmatory testing before systemic therapy should be reconsidered and replaced with recommendations tailored to specific therapies.