LAUSR

To the Editor, Onychomycosis is common in the US, affecting > 12% of the population [1]. Efinaconazole (Jublia®) and tavaborole (Kerydin®) are topical antifungal treatments that were approved by the US FDA in 2014 for onychomycosis. These novel agents, by some estimates, may incur costs of US$12,000–$180,000 per-treatment success [2]. Recent studies demonstrated that new agents such as efinaconazole are among the most expensive treatment modalities for onychomycosis compared with generic medications [3, 4]. We sought to characterize real-world utilization and expenditure patterns for these medications. We examined data from the Center for Medicare and Medicaid Services’ (CMS) Part D 2013–2016 Public Use Files, including prescriber specialty and prescription year. Number and list prices of prescriptions were assessed for efinaconazole and tavaborole, as well as terbinafine (Lamisil®) and ciclopirox (Penlac®, Ciclodan®, Loprox®) for comparison. Prices were adjusted for inflation to 2016 US dollars using the Bureau of Labor Statistics’ Consumer Price Index [5], and compared between years for each medication. Total expenditures, defined as the aggregate yearly cost of Medicare claims for all prescribers of a particular drug, were recorded for each calendar year. Student’s t tests were performed between mean expenditure per prescriber between years. Of note, efinaconazole and tavaborole were available only for the final 3 and 2 years of data, respectively. The most frequent prescribers of all antifungals were podiatrists, followed by nurse practitioners, internal medicine doctors, and dermatologists (Table 1). Terbinafine and ciclopirox were prescribed most frequently by all provider types. Podiatrists prescribed the novel drugs efinaconazole and tavaborole more often than all other clinicians combined. The total number of prescriptions increased annually between 2013 and 2016 for each of the four drugs, with the highest growth (absolute annualized increase; relative annualized percentage) in the relative rate of utilization for efinaconazole (3992, 500%), followed by tavaborole (1285, 73.7%), terbinafine (21,374, 10.3%) and ciclopirox (21,200, 8.7%). Utilization of terbinafine and ciclopirox grew at the fastest rate among nurse practitioners (3036, 22.7%; and 5551, 44.9%, respectively). Growth in utilization of efinaconazole and tavaborole was highest among podiatrists (4633, 496%) and physician assistants (92, 192%), respectively. Total expenditures (Fig. 1) for these prescriptions increased annually between 2013 and 2016 for each of the four drugs, with the highest growth of expenditure for efinaconazole (645%), followed by tavaborole (97.6%), terbinafine (3.1%), and ciclopirox (3.1%). Expenditure on efinaconazole grew at the fastest rate among podiatrists (674%) and general practitioners (408%), while tavaborole expenditure increased most among physician assistants (202%) and podiatrists (102%). Expenditure on terbinafine and ciclopirox grew most among nurse practitioners (22.7% and 44.9%, respectively). Mean prescriber expenditure on all drugs combined increased significantly from 2014 to 2015 for dermatologists (p < 0.0001) and podiatrists (p = 0.0001), after the introduction of both efinaconazole and tavaborole. Notably, expenditure grew at a faster rate than utilization for efinaconazole (1.3:1) and tavaborole (1.3:1), but not terbinafine (0.3:1) or ciclopirox (0.4:1). Overall, annualized growth rates for antifungal medication claims (10%) paralleled growth in the number of prescribers (11%); however, total spending grew disproportionately for all clinicians (18%). * Jonathan I. Silverberg [email protected]