Cost-effectiveness of diagnostic tests for toenail onychomycosis: A repeated-measure, single-blinded, cross-sectional evaluation of 7 diagnostic tests

Cost-effectiveness of Confirmatory Testing Before Treatment of Onychomycosis

“…Models 2 and 3 were chosen based on multiple studies and international guidelines that recommend the use of PAS for out-of-office testing and in-clinic KOH screening as the least costly, most broadly available in-office procedure. 1,5,[11][12][13][14][15][16] Assigning Cost and Classification Probabilities…”

Confirmatory Testing for Onychomycosis—Reply

“…An erroneous diagnosis would be even more detrimental with malignant nail conditions, such as squamous cell carcinoma and melanoma. 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.…”

“…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.…”

“…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.…”

“…However, if a dermatologist's clinical diagnosis is onychomycosis, he or she is correct between 65% and 95% of the time. 2,3,6 The quoted baseline 4% prevalence of onychomycosis in society is irrelevant because our study focuses on the prevalence among patients who have…”