Global prevalence of onychomycosis in general and special populations: An updated perspective.

ABSTRACT

BACKGROUND: Onychomycosis is a chronic nail disorder commonly seen by healthcare providers; toenail involvement in particular presents a treatment challenge. OBJECTIVE: To provide an updated estimate on the prevalence of toenail onychomycosis. METHODS: We conducted a literature search using PubMed, Embase and Web of Science. Studies reporting mycology-confirmed diagnoses were included and stratified into (a) populations-based studies, and studies that included (b) clinically un-suspected and (c) clinically suspected patients. RESULTS: A total of 108 studies were included. Based on studies that examined clinically un-suspected patients (i.e., with or without clinical features suggestive of onychomycosis), the pooled prevalence rate of toenail onychomycosis caused by dermatophytes was 4% (95% CI 3-5) among the general population; special populations with a heightened risk include knee osteoarthritis patients (RR 14.6 [95% CI 13.0-16.5]), chronic venous disease patients (RR 5.6 [95% CI 3.7-8.1]), renal transplant patients (RR 4.7 [95% CI 3.3-6.5]), geriatric patients (RR 4.7 [95% CI 4.4-4.9]), HIV-positive patients (RR 3.7 [95% CI 2.9-4.7]), lupus erythematosus patients (RR 3.1 [95% CI 1.2-6.3]), diabetic patients (RR 2.8 [95% CI 2.4-3.3]) and hemodialysis patients (RR 2.8 [95% CI 1.9-4.0]). The prevalence of onychomycosis in clinically suspected patients was significantly higher likely due to sampling bias. A high degree of variability was found in a limited number of population-based studies indicating that certain pockets of the population may be more predisposed to onychomycosis. The diagnosis of non-dermatophyte mould onychomycosis requires repeat sampling to rule out contaminants or commensal organisms; a significant difference was found between studies that performed single sampling versus repeat sampling. The advent of PCR diagnosis results in improved detection rates for dermatophytes compared to culture. CONCLUSION: Onychomycosis is an underrecognized healthcare burden. Further population-based studies using standardized PCR methods are warranted.