Comparison of diagnostic methods in the evaluation of onychomycosis

Confirmatory Testing for Onychomycosis—Reply

“…2 Furthermore, while highly trained dermatologists and podiatrists may be able to make the diagnosis of onychomycosis clinically in many cases, general practitioners and physician extenders would have less diagnostic precision. All things considered, treatment for presumed onychomycosis without laboratory confirmation may cause misdiagnosis, serious complications, 3 and medicolegal costs.…”

“…We strongly advocate that physicians confirm the diagnosis before initiating treatment in all cases of nail dystrophy. 3 To the Editor Mikailov and colleagues 1 propose that the empirical treatment of onychomycosis with terbinafine without confirmatory testing is cost-effective. While the approach may be reasonable when disease prevalence is exceedingly high, prescribing medications with known adverse effects, some serious, leads to delay in correct treatment and unnecessary therapy for patients with dystrophic nails who do not have onychomycosis.…”

“…While the approach may be reasonable when disease prevalence is exceedingly high, prescribing medications with known adverse effects, some serious, leads to delay in correct treatment and unnecessary therapy for patients with dystrophic nails who do not have onychomycosis. In fact, only about half of dystrophic nails are caused by fungi 2,3 ; the other half are manifestations of psoriasis, lichen planus, and trauma, among other causes. If empirical treatment is provided for clinically suspected onychomycosis in dystrophic nails, correct treatment is delivered only half the time, the same probability as a random coin flip.…”

“…Furthermore, recent metaanalyses for the prevalence of onychomycosis in Europe and North America estimate it to be only 4%, with previous reports of 7% to 14% in North America. [3][4][5] Mikailov et al 1 also discuss the cost savings for liver function test monitoring during terbinafine therapy. While the incidence of apparent liver injury from terbinafine is low, one needs to consider quality of life issues and financial repercussions of other adverse effects such as dysgeusia, gastrointestinal upset, and more serious systemic manifestations including DRESS syndrome (drug reaction with eosinophilia and systemic symptoms), Stevens-Johnson syndrome, and toxic epidermal necrolysis.…”

“…However, potassium hydroxide and periodic acid-Schiff are the most widely used and appropriate tests to consider in the initial workup, as fungal cultures have such poor sensitivity, poor negative predictive value, and delayed time to diagnosis. 2,3 Of course, if a nondermatophyte is suspected, such as in refractory disease, a culture should be taken. Although primary care physicians are less accurate than dermatologists in their clinical diagnosis of onychomycosis, our data suggest that empirical treatment is still favored at their level of accuracy.…”