Pediatric Onychomycosis Prevalence: A Systematic Review
Overview
Onychomycosis, a prevalent nail ailment in adults, has historically been considered rare in children, despite scattered and diverse data. Recent studies, however, hint at an increasing prevalence of onychomycosis in children. This review aimed to address this issue, with two authors individually scouring PubMed, Embase, and Cochrane Library for relevant epidemiological articles. Adhering to PRISMA guidelines, a total of 1042 articles were identified, of which 23 met the eligibility criteria. With one article encompassing two studies, the review eventually included 24 studies. Among these, 17 focused on onychomycosis prevalence in children within the general population, while seven delved into cases among children visiting dermatological and pediatric departments or clinics.
Across these studies, onychomycosis prevalence ranged from 0% to 7.66%. A modest overall increase of 0.66% was observed between 1972 and 2014, although this change wasn’t statistically significant in population studies. This review underscores the emerging trend of elevated onychomycosis prevalence in children, although the limited number of studies warrants caution. Notably, the data suggests that prevalence rises with age, often accompanied by co-infection with tinea pedis, as noted in 25% of the studies.
Trichophyton rubrum emerged as the most common pathogen, mirroring the patterns seen in adults. Moreover, onychomycosis exhibited a greater prevalence in toenails compared to fingernails. This review thus emphasizes that the general characteristics of onychomycosis in children share similarities with those observed in adults.
Introduction
Fungal infection affecting the nails constitutes a notable portion (15%–40%) of overall nail disorders, prominently impacting adults. While onychomycosis is commonly observed in adults, its occurrence in children has historically been considered uncommon. However, recent indications suggest a potential rise in pediatric onychomycosis over the past few decades. The majority of studies addressing this concern are retrospective and rely on medical records or laboratory data.
Detecting and treating pediatric onychomycosis is of paramount importance for various reasons. Early intervention is critical to halt disease progression, potentially leading to higher cure rates. Mild cases in children can often be effectively managed with topical treatments, which have been FDA-approved for use in those ≥6 or ≥12 years of age, depending on the specific medication.
Notably, topical therapy is deemed more efficacious in children compared to adults, showcasing a lower risk of side effects and systemic exposure. In cases of heightened severity, systemic treatment is introduced, although this approach presents risks of drug interactions and adverse events. Worth mentioning is the lack of licensed systemic antifungal therapy for treating onychomycosis in children.
The primary goal of this systematic review is to delve into the global prevalence of onychomycosis among children. This pursuit is vital in shaping our understanding of the evolving landscape of pediatric onychomycosis and its associated considerations for diagnosis and treatment.
Method
This systematic review focuses on analyzing the prevalence of onychomycosis in the pediatric population (ages 0–18 years), adhering to the PRISMA guidelines for reporting. The review’s registration with PROSPERO was completed on April 11, 2021, with the assigned registration number CRD42021241810. Extensive literature searches were conducted on March 11, 2021, across PubMed, Embase, and Cochrane Library databases.
The search process was diligently carried out by two authors (SVJ & AM) independently, utilizing the literature search tool Rayyan. In cases of disagreement between the authors, the senior author (DMS) was consulted for resolution. This meticulous approach ensures the review’s comprehensiveness and adherence to established guidelines, ultimately contributing to the robustness of the findings.
Inclusion Criteria
The inclusion criteria for this study involved selecting peer-reviewed articles published in English or Danish, specifically focusing on onychomycosis prevalence in children. To ensure statistical significance, only studies encompassing 100 or more children under the age of 18 were considered eligible. This rigorous approach aimed to provide a comprehensive and reliable understanding of onychomycosis prevalence within the pediatric population.
Exclusion Criteria
This study’s scope excluded research involving specific patient groups like those with diabetes or immunodeficiency. Additionally, studies where the entire population had pre-existing onychomycosis or superficial mycosis upon study entry were not considered. The review also disregarded studies centered on a single causal agent or those conducting laboratory surveys of specimens from suspected onychomycosis patients. This rigorous exclusion criteria ensured that the study’s findings remained focused on general prevalence trends within the target pediatric population.
Statistical Analysis
The review involved the extraction of relevant data by a designated researcher (SVJ) onto a prearranged Excel sheet. This data encompassed onychomycosis prevalence, publication year, country of origin, study population specifics, diagnostic methods employed, and additional factors such as prevalence comparison between fingernails and toenails, risk factors, etiological agents, and concomitant mycosis or skin diseases. A narrative synthesis approach was taken for data reporting due to the heterogeneity in study designs, precluding meta-analysis. To assess the relationship between time and onychomycosis prevalence, linear regression was applied using RStudio Version 1.2.1335, contributing to a comprehensive evaluation of potential trends over time.
Result
This systematic review encompassed a total of 1042 articles from databases including Embase, PubMed, and Cochrane Library. After eliminating duplicates (237), 805 articles underwent screening. Among these, 680 were considered unrelated, leading to a closer examination of 125 articles. Eventually, 23 articles with 24 studies were deemed suitable for inclusion.
The analyzed studies spanned a 44-year period and encompassed 17 studies exploring onychomycosis prevalence in the general population and seven focusing on pediatric or dermatological clinics or departments. In population-based studies, onychomycosis prevalence among children ranged from 0% to 3.37%, whereas studies from clinics or departments exhibited prevalence varying from 0% to 0.53%, based on clinical observation, microscopy, and culture.
Participant numbers varied significantly, from 100 to 32,235 children. Most participants in population-based studies were aged 5 to 16 years, while those in clinics or departments spanned ages 0 to 18 years. Gender-wise, males constituted 44.7% to 100%, with a mean prevalence of 51.9% (28,507 male children out of 65,189). A study indicated that boys had a higher likelihood of onychomycosis than girls (p = 0.001, male frequency: 54.5%).
Clinical diagnosis was common across studies, often confirmed by microscopy and culture (17/24). Prevalence ranged from 0% to 3.37% for combined clinical diagnosis, microscopy, and culture. Additionally, studies relying on clinical diagnosis and microscopy only had prevalence rates between 0% and 0.25%. Some solely relied on clinical diagnosis, yielding rates of 0.03% to 7.66%, with the highest rates recorded in studies from the Solomon Islands (7.66%), Ethiopia (7.59%), and Brazil (5.01%).
Over time, the prevalence of onychomycosis showed a notable increase, with rates rising from 0.22% in 1972 to 0.29% to 0.88% in 2014-2016. For onychomycosis prevalence in Turkey, six studies from 2002 to 2013 indicated rates of 0% to 0.33%, with a slight uptick from 2004 to 2013.
Geographical distribution was wide-ranging, spanning multiple continents. Notably, the highest prevalence was mycologically confirmed at 3.37% in a 2009 Peruvian study. Similarly, Mexico (0.75%), Israel (0.87%), and Nigeria (0.88%) reported high prevalence rates. Clinical diagnoses only, prevalent in some studies, exhibited higher rates, such as Ethiopia (7.59%) and the Solomon Islands (7.66%). Geographically, Europe (0% to 0.20%), North America (0% to 0.75%), and West Asia (0% to 0.87%) showcased varying prevalence ranges.
Some studies reported concomitant infections on other body sites (tinea pedis or tinea capitis), while dermatophytes were more common than yeasts. T. rubrum was the predominant dermatophyte species, while common yeasts included C. albicans and C. glabrata. The distribution of onychomycosis in fingernails versus toenails was also examined, indicating varying prevalence in different studies.
In summary, this systematic review showcased an apparent increase in onychomycosis prevalence among children over time. It also highlighted the significance of accurate diagnostic methods and the influence of geography, age, and gender on prevalence rates.
Conclusion
This systematic review provides evidence suggesting a potential rise in the prevalence of onychomycosis among children, particularly during the years 2000-2015. However, this trend lacks statistical significance based on available data. Diagnostic accuracy holds paramount importance in the pediatric population, as only around 15.5% of nail issues in children are attributed to onychomycosis. The majority of studies (83% out of 24) confirmed onychomycosis suspicion through mycological examination.
Despite variations in sampling methods, participant numbers, gender, cultural factors like footwear and sports, the prevalence data seem relatively consistent. The initial hypothesis of higher prevalence rates in dermatology centers and clinics than in background populations was not substantiated. The variation in age groups examined, warmer geographical locations, and potential confounders like footwear and access to healthcare may impact prevalence rates.
Onychomycosis tends to be more common in toenails than fingernails in both children and adults. The transfer from tinea pedis to toenails, observed in adult studies, is supported by findings where tinea pedis and onychomycosis coexist. The most prevalent pathogen identified is T. rubrum, consistent with findings in adults. Yeast-caused onychomycosis is more prevalent in fingernails, particularly in immunosuppressed individuals and neonates. Curiously, most yeast-related cases in supposedly healthy school children were found in toenails.
Exploring factors like moist shoe environments, genetic predisposition, and diabetes as associated factors would be insightful. The review highlights certain limitations, including population size requirements, age group differences, and incomplete testing for various pathogens.
In conclusion, this systematic review indicates a potential increase in onychomycosis prevalence among children, although not statistically significant with available data. It emphasizes the importance of considering childhood onychomycoses, especially when concurrent tinea pedis is present. The prevalent pathogen, T. rubrum, and the higher prevalence of toenail infection compared to fingernails are notable observations.
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