Onychomycosis: Epidemiology, Diagnosis, and Treatment in a Changing Landscape

March 2015 | Volume 14 | Issue 3 | Original Article | 223 | Copyright © March 2015


Theodore Rosen MD,a Sheila Fallon Friedlander MD,b Leon Kircik MD,c Matthew J. Zirwas MD,d
Linda Stein Gold MD,e Neal Bhatia MD,f Aditya K. Gupta MD PhD MBAg

aDepartment of Dermatology, Baylor College of Medicine, Houston, TX
bDepartment of Pediatrics and Medicine (Dermatology), School of Medicine, University of California and Rady Children’s Hospital, San Diego, CA
cIcahn School of Medicine at Mount Sinai, New York, NY; Indiana University School of Medicine, Indianapolis, IN; Physicians Skin Care,
PLLC, Louisville, KY
dDivision of Dermatology, The Ohio State University Medical Center, Columbus, OH
eDepartment of Dermatology, Henry Ford Health Systems, Detroit, MI
fDivision of Dermatology, Harbor UCLA Medical Center, Los Angeles, CA
gDepartment of Medicine, University of Toronto, Toronto, ON

Abstract
Onychomycosis is an often overlooked and/or undertreated disease. This may be in part due to an under appreciation among both physicians and patients of its impact on quality of life and the potential for significant complications, from tinea corporis and cruris, to bacterial superinfection. Some health care providers are unaware of the effective low-risk treatments currently available. Changing demographic characteristics such as the relative aging of the population; the increasing prevalence of diabetes and peripheral vascular disease, and widespread iatrogenic immunosuppression; and changes in lifestyle practices such as earlier and greater participation in sports, are likely to lead to an increased prevalence of onychomycosis in both adults and children. Two topical onychomycosis treatments, efinaconazole 10% solution, and tavaborole 5% solution were recently approved by the FDA. This article reviews the state of knowledge and describes, briefly, these new treatment options.

J Drugs Dermatol. 2015;14(3):223-228.

INTRODUCTION

Nearly half (48%) of nail abnormalities result from documented onychomycosis,1 with toenails affected most often (toenail-fingernail ratio: 10.6).2 In addition to its cosmetic impact, onychomycosis can be painful and thereby significantly affect patients’ quality of life (QoL).3,4 These effects increase with disease duration and extent and/or number of toenails affected. The average number of toenails involved is 5, with approximately 15% of patients having all 10 affected.4 Spontaneous resolution is rare and disease duration is often >5 years.3,4
Treatment paradigms will likely shift due to the introduction of new topical agents and the increasing recognition that all ages are at risk for fungal nail infections. This paper will review the epidemiology, diagnosis, and management of onychomycosis in the context of these new developments.

Epidemiology

Disease prevalence estimates vary widely across studies; however, a recent meta-analysis calculated a rate of approximately 4% in North America/Europe.2 Between-study variation may be due to differences in study location (prevalence varies with geography/cultural practices), study methodology, and population source (ie, patients with nail complaints, mycological samples, medical office visits, or unselected/general population). Prevalence is clearly higher in males and increases with age.1,5,6
Risk factors for onychomycosis include tinea pedis,6,7 nail trauma,8 diabetes,8-11 peripheral vascular disease (PVD),5,8,12,13 and personal/family history of onychomycosis.7,8 Significant associations also exist for psoriasis.7,14 These conditions may contribute to onychomycosis susceptibility via slower/poor nail growth (due to age or poor circulation), immune suppression, and/or nail trauma (diabetic neuropathy, psoriatic nail changes). Vasoconstriction and/or hypoxemia due to nicotine exposure or PVD may further increase the risk of onychomycosis.12
The incidence of onychomycosis will likely rise due to projected increases in important risk factors such as age, diabetes, and PVD.
Diabetes
Approximately half (46-50%) of patients with diabetes have toenail abnormalities,9,15 of which 57-65% are due to onychomycosis9,11 (13-30% prevalence9,15,16). Similar to the general population, older age,9,16 male gender,9 PVD,9 and family history of onychomycosis9,15 are all significant risk factors among diabetics. Further risk factors include immunosuppression,9
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