Cost-effectiveness of diagnostic tests for toenail onychomycosis: a repeated-measure, single-blinded, cross-sectional evaluation of 7 diagnostic tests.
OBJECTIVE
Our purpose was to estimate and compare the cost-effectiveness of the most commonly used diagnostic tests for onychomycosis: potassium hydroxide preparation (KOH), interpreted both by a dermatologist (KOH-CLINIC) and a laboratory technician (KOH-LAB); KOH with dimethyl sulfoxide (KOH-DMSO) and with chlorazol black E (KOH-CBE), interpreted by a dermatologist; culture using dermatophyte test medium, culture with Mycobiotic and Inhibitory Mold Agar (Cx); and histopathologic analysis using periodic acid-Schiff stain (PAS).


METHODS
This was a repeated-measure, blinded, cross-sectional study conducted at the Minneapolis Veterans Affairs Medical Center. Inclusion criteria included: at least one toenail with 25% or more clinical disease, which was defined as subungual debris with onycholysis and/or onychauxis. Exclusion criteria included other nail dystrophies, use of oral antifungal medication for 2 months or longer within the past year, or topical ciclopirox lacquer within 6 weeks of enrollment. The main outcome measure was the cost-effectiveness (Medicare and non-Medicare costs) of 7 diagnostic tests. Sensitivity (at least 3 positive tests) was the unit of effectiveness.


RESULTS
Two hundred four participants were enrolled; their average age was 69.5 years and 95.5% were male. PAS was the most sensitive test (98.8%); it was statistically significantly more sensitive than all other diagnostic tests except KOH-CBE (94.3%). Dermatophye test medium was the least sensitive test (57.3%). KOH-CBE was statistically significantly more cost effective than any other test, with the exception of KOH-CLINIC and KOH-LAB. PAS was the least cost effective.


CONCLUSIONS
Test specificities were not evaluated.


CONCLUSIONS
KOH-CBE should be the test of choice for practitioners confident in interpreting KOH preparations because of its combination of high sensitivity and cost-effectiveness.
Lilly
Kia K
KK
University of Minnesota, Minneapolis, Minnesota, USA.
Koshnick
Rebecca L
RL
Grill
Joseph P
JP
Khalil
Zena M
ZM
Nelson
David B
DB
Warshaw
Erin M
EM
D000368:Aged; D003362:Cost-Benefit Analysis; D003430:Cross-Sectional Studies; D003955:Diagnostic Tests, Routine / Q000191:economics / Q000379:methods; D005260:Female; D005533:Foot Dermatoses / Q000175:diagnosis* / Q000191:economics*; D006801:Humans; D008297:Male; D014009:Onychomycosis / Q000175:diagnosis* / Q000191:economics*; D012680:Sensitivity and Specificity; D016037:Single-Blind Method