The Sensitivity and Specificity of Potassium Hydroxide Smear and Fungal Culture Relative to Clinical Assessment in the Evaluation of Tinea Pedis: A Pooled Analysis

Jacob Oren Levitt,Howard Yanofsky,Arash Akhavan,Barrie H Levitt

doi:10.1155/2010/764843

Abstract

Background. There are relatively few studies published examining the sensitivity and specificity of potassium hydroxide (KOH) smear and fungal culture examination of tinea pedis. Objective. To evaluate the sensitivity and specificity of KOH smear and fungal culture for diagnosing tinea pedis. Methods. A pooled analysis of data from five similarly conducted bioequivalence trials for antifungal drugs was performed. Data from 460 patients enrolled in the vehicle arms of these studies with clinical diagnosis of tinea pedis supported by positive fungal culture were analyzed 6 weeks after initiation of the study to determine the sensitivity and specificity of KOH smear and fungal culture. Results. Using clinical assessment as the gold standard, the sensitivities for KOH smear and culture were 73.3% (95% CI: 66.3 to 79.5%) and 41.7% (34.6 to 49.1%), respectively. The respective specificities for culture and KOH smear were 77.7% (72.2 to 82.5%) and 42.5% (36.6 to 48.6%). Conclusion. KOH smear and fungal culture are complementary diagnostic tests for tinea pedis, with the former being the more sensitive test of the two, and the latter being more specific.

Highlights

Tinea pedis is a dermatophyte infection of the plantar feet or toe web spaces most commonly caused by Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum [1]
While we often rely on KOH smear and/or culture in the diagnosis of tinea pedis, the sensitivity and specificity of these procedures have only been reported in a limited number of studies
Using clinical assessment as the gold standard, the sensitivities for KOH smear and culture were 73.3% and 41.7% (34.6 to 49.1%), respectively (Table 5)

Summary

Introduction

Tinea pedis is a dermatophyte infection of the plantar feet or toe web spaces most commonly caused by Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum [1]. Two commonly used laboratory methods for the diagnosis of tinea pedis are fungal culture and potassium hydroxide (KOH) examination of skin scrapings for fungal elements. There are relatively few studies published examining the sensitivity and specificity of potassium hydroxide (KOH) smear and fungal culture examination of tinea pedis. To evaluate the sensitivity and specificity of KOH smear and fungal culture for diagnosing tinea pedis. Data from 460 patients enrolled in the vehicle arms of these studies with clinical diagnosis of tinea pedis supported by positive fungal culture were analyzed 6 weeks after initiation of the study to determine the sensitivity and specificity of KOH smear and fungal culture. KOH smear and fungal culture are complementary diagnostic tests for tinea pedis, with the former being the more sensitive test of the two, and the latter being more specific

Methods

Results

Conclusion