1. INTRODUCTION
However, it has been suggested that the incidence of onychomycosis in children may have increased over the past three decades.2–4 However, most studies are retrospective and based on information from medical records or laboratory data.2– 4
Onychomycosis in pediatrics is important to diagnose and treat for several reasons. Early detection and treatment of onychomycosis is crucial to preventing disease progression.1 Additionally, early treatment of onychomycosis may result in higher cure rates. Mild onychomycosis can be treated topically with good results in children.
Few antifungal therapies are licensed for the treatment of onychomycosis in children. Topical therapy is used as monotherapy for milder cases and is approved by the US Food and Drug Administration (FDA) for ages ≥12 years (ciclopirox) and ≥6 years (efinaconazole, tavaborole). Treatment with topical therapy is reported to be more effective in children than in adults,5 with low risk of side effects and low systemic exposure. Systemic treatment is added when the disease is more severe but has a higher risk of drug interaction and adverse events. No systemic antifungal therapy is approved for the treatment of onychomycosis in children.5
The aim of this systematic review is to explore the global prevalence of onychomycosis in children.
2. MATERIALS AND METHODS
This systematic review focuses on the prevalence of onychomycosis in children (0-18 years) and is reported according to PRISMA guidelines.6 It was registered with PROSPERO on April 11, 2021 under number CRD42021241810. Details of the protocol can be accessed at www. crd.york.ac.uk/prospero/display_record.php?ID=CRD42021241810.
The PubMed, Embase, and Cochrane Library databases were searched for articles on March 11, 2021. Two authors independently conducted the search using the Rayyan literature search tool.7 In case of disagreement, the lead author was consulted. .
2.1 Inclusion criteria
Studies reporting the prevalence of onychomycosis in children published in a peer-reviewed journal in English or Danish. Only studies with 100 or more children (>18 years) were included.
2.2 Exclusion criteria
We excluded studies with special patient groups (e.g., diabetes and immunodeficiency) and studies in which the entire study population had or was suspected of having onychomycosis or a superficial mycosis before entering the study. Studies focusing on a specific etiological agent or laboratory studies of samples from patients with suspected onychomycosis were also excluded.
2.3 Data collection and statistics
Data were collected on the prevalence of onychomycosis, year of publication, country, type and size of the study population, method of diagnosis, prevalence of onychomycosis in fingernails compared to fingernails. feet, risk factors, etiological agents, concomitant mycosis or skin disease were extracted by one researcher to a pre-designed Excel sheet. Data were reported as a narrative synthesis. Meta-analysis could not be performed due to heterogeneity in study designs. A linear regression was fitted to the data on the prevalence of onychomycosis in children in percentage (%) as a function of time, using the program RStudio Version 1.2.1335 (RStudio ©, Boston) to determine if the time variable could explain the change in prevalence.
3. RESULTS
3.1 Bibliographic search
A total of 1042 articles were identified by searching Embase, PubMed and the Cochrane Library, of which 237 articles were duplicates and 805 were screened. Of these, 680 were out of scope and 125 articles were read. In total 23 articles were included in the review.
The 23 articles with 24 studies were conducted over a period of 44 years. A total of 17 studies explored the prevalence of onychomycosis in the general population, while seven studies investigated the prevalence of onychomycosis among children attending a pediatric or dermatological clinic or department. In population studies, the prevalence of onychomycosis in children ranged from 0% to 3.37% and in studies of pediatric or dermatological clinics or departments the prevalence ranged from 0% to 0.53%.
The number of children included in the studies ranged from 100 to 32,235 children, and the majority of children included were in the age range of 5 to 16 years in population-based studies and 0 to 18 years in clinics or dermatological departments, respectively. .
3.2 Demographic data
Two studies showed an association between an increase in the prevalence of onychomycosis and increasing age in children.8,9 Unfortunately, separate details on age and onychomycosis were not available to allow further analysis.
For studies that provided sex data, the frequency of males ranged from 44.7% to 100%, and the mean prevalence of males in the included studies was 51.9% (28,507 male children/65,189 male children). It was not possible to extract the exact male frequency of onychomycosis, but one study found that boys were more likely to have onychomycosis than girls (p = 0.001, male frequency: 54.5%).10
3.3 Diagnostic evaluation
All studies reported on the clinical diagnosis (nail changes) and most studies confirmed the clinical diagnosis of onychomycosis with microscopy in combination with culture (17/24).8–23 The prevalence of onychomycosis in studies using a combination of microscopy and culture ranged from 0 to 3.37%.8–23
Three studies were based on clinical diagnosis and microscopy alone with prevalence rates ranging from 0 to 0.25%.24–26
Three studies were based on clinical diagnosis alone.27–29 One study reported that only half of the cases had mycological confirmation of onychomycosis, therefore all cases were reported as clinically diagnosed.30
Prevalence rates in studies primarily based on clinical diagnosis ranged from 0.03% to 7.66%27–30, and of these, three reported the highest prevalence rates in the current review (7 .66% Solomon Islands 1985,28 7.59% Ethiopia 2010 and 5.01% 2013 Brazil30 respectively)
3.4 Distribution over time
The studies were published during the years 1972–2016 and the prevalence increased from 0.22% in 197217 to between 0.29% and 0.88% in 2014–16.15,16
Focusing on the prevalence of childhood onychomycosis in Turkey only, this review identified six studies published during the years 2002–2013.8–11,24,26 The prevalence of onychomycosis among Turkish children ranged from 0% to 0.33% and showed a small increase in prevalence between 2004 and 2013.8,11
3.5 Geographic distribution
The included studies from dermatology clinics, departments and hospitals are from South America (Brazil), North America (Canada and USA), Europe (UK and a cooperative study [the Achilles project] conducted in Belgium, Republic Czech, Germany, Great Britain, Greece, Hungary and Luxembourg). Population studies were carried out in Western Asia (Turkey, Egypt, Israel), Oceania (Solomon Islands), East Africa (Ethiopia), South America (Peru), Europe (Spain, United Kingdom, Finland), West Africa (Nigeria), South Asia (India) and North America (Mexico).
The highest prevalence of onychomycosis in children diagnosed mycologically was 3.37% in a study conducted in Peru in 2009.14 This prevalence was much higher than that reported in similar studies that used the same diagnostic methods in other countries (0%– 0.88 %).8–13,15 –21,23 In addition to the prevalence in Peru, the highest prevalences, diagnosed clinically and with microscopy and culture, were in Mexico 0.75%,23 Israel 0.87%13 and Nigeria 0.88%. .15 In studies with clinical diagnosis only (without mycological confirmation) the prevalence is generally higher and up to 7.59% in Ethiopia 27 and 7.66% from 1985 in the Solomon Islands.28
The prevalence of mycologically confirmed onychomycosis in Europe ranged between 0% and 0.20%,12,18,19,31 in North America between 0% and 0.75%,16,20,21,23. 25 and in Western Asia from 0% to 0.87%.8–11,13,24,26
3.6 Onychomycosis with concomitant skin infections
A total of seven studies reported on co-infection in other parts of the body (tinea pedis [6/105]8,9,12,14,20,23 or tinea capitis [1/105]). In two studies, no concomitant mycosis was found,18,24 and in one study, no concomitant tinea pedis was found.10
3.7 Fungal pathogens
Dermatophytes (55/95) were more common than yeasts (40/95) and the most prevalent dermatophyte species were T. rubrum (39/55), T. mentagrophytes (4/55), including a co-infection with T. tonsurans and E. floccosum (3/55). The most common yeasts isolated were C. albicans (11/40) and C. glabrata (11/40). The only study that specified nail isolates reported C. albicans (1/4), C. glabrata (2/4), and C. tropicalis (1/4) in four patients.9 Trichosporon spp. (n = 13/40) were isolated in two studies from Turkey.8,10
3.8 Prevalence of onychomycosis in fingernails compared to toenails
The distribution of onychomycosis infecting fingernails compared to toenails was examined in six studies.8–10,14,15,20 0% to 0.75%. In five studies,8–10,14,20 onychomycosis was more prevalent in toenails than in fingernails, and in one study it was more prevalent in fingernails.15 In six studies only They examined the toenails.12,13,16,22–24
4. DISCUSSION
This systematic review supports the hypothesis of a generally increasing prevalence of onychomycosis in children, especially during the years 2000–2015.
Estimated prevalence rates are based on the diagnosis of onychomycosis in a given sample. Diagnostic accuracy in the pediatric population is of utmost importance since only about 15.5% of nail dystrophies in children are caused by onychomycosis.32 Most studies8–26 (83% [20/24]) confirmed the of onychomycosis by mycological examination.
The data appear regardless of the sampling method despite the large variation in the number or sex of participants, cultural differences such as type of footwear, sports activities, etc. that may affect prevalence.
The authors expected to find a higher prevalence rate of onychomycosis in dermatology centers and clinics than in the general population,33 represented by studies carried out in schools and in the general population, but this hypothesis remains unsupported. This lack of difference in prevalence rates could be influenced by the difference in the age groups examined, where most hospital and clinic studies included younger children aged 0 to 4 years (6/7), 16,20 –22, 25,30 while most background population studies (14/17) included older school-aged children. 8–10,13–15,17–19, 23, 24, 26, 27,29
Additionally, geography may play a role since the highest prevalence occurs in warmer countries. However, the analysis does not allow the data to be adjusted for potential confounders such as footwear, access to medical care, and similar factors that may influence the outcome.
Topographically, onychomycosis is generally more prevalent in the toenails than the fingernails in both children and adults.1 Transfer apparently occurs when tinea pedis spreads to the toenails, which is also has been described in studies of adults.34 This could be correlated with the six studies where tinea pedis and onychomycosis were concomitant.8,9,12,14,20,23
The dermatophyte T. rubrum was the most prevalent pathogen identified (39/153), 36% of the total cases confirmed with culture, which is in good agreement with previous studies in adults.1,33 Yeasts represented 26% (40 /153) of infections, represented by Trichosporon spp. (13/40), C. albicans (11/40), C. glabrata (11/40), Rhodotorula spp. (3/40), C. parapsilosis (1/40), C. tropicalis (1/40) isolated mainly in Turkish studies.8–10
Onychomycosis caused by yeast is more common in the fingernails than in the toenails and is also more common in immunosuppressed patients and neonates.1,35 Therefore, it is interesting that the majority of cases of onychomycosis caused by yeast yeasts were found on the toenails (35/39) of supposedly healthy schoolchildren in the Turkish studies.8–10 An exploration of associated factors such as, for example, wet environment of footwear, genetic predisposition, diabetes would be of interest.
In 38% of the cases, the species of the fungus was not determined in children. Additional limitations of these results are the population size limit of a minimum of 100 children, a difference in age groups between children seen in dermatology centers and clinics (younger) compared to children from older populations. reference (mainly older school-age children) and lack of testing for yeast and non-dermatophytic molds, but also the prevalence of familial diseases as an indicator of both increased exposure and genetic predisposition.
All studies with a prevalence of 0% (5/5) had study populations of 100 to 200 children.11,18,19,25,26 This indicates that the limit of at least 100 children in the study population should have been set above 200 instead. Only three studies examined children in the age range of 0 to 18 years20–22, while the other studies had a narrower age range. In hospital and clinic studies, the majority (6/7) of children included ages 0–4 to 18 years.16,20–22,25,30 However, most reference population studies ( 14/17) only included schoolchildren.8–10,13–15,17–19,23,24,26,27,29
Nine of the studies only investigated dermatophytes (and C. albicans),12,13,15,17–21 and did not include the prevalence of onychomycosis due to other pathogens, such as non-albicans yeasts and non-dermatophyte molds.
5. CONCLUSION In conclusion, the systematic review suggests a trend of increasing prevalence of onychomycosis in children; however, this trend is not statistically significant based on the available data. Childhood onychomycosis has many similarities to adult onychomycosis; It should be considered when the child presents tinea pedis. The most common pathogen is T. rubrum and infection of toenails is more common compared to fingernails. |
Comment: Onychomycosis is quite common in adults but is described as uncommon in children. However, the data is not conclusive. Studies suggest that the prevalence of onychomycosis is increasing in children and the aim of this review was to examine this.
Two authors individually searched for the epidemiology and prevalence of onychomycosis in children. In total, 1042 articles were identified, of which 23 were eligible for inclusion. The present review supports a trend towards a higher prevalence of onychomycosis in children, although a paucity of studies is highlighted. Data suggest an increasing prevalence of onychomycosis with age and co-infection with tinea pedis. The most commonly reported pathogen was Trichophyton rubrum and onychomycosis was more common in toenails than in fingernails. The general characteristics of onychomycosis in children are similar to those described in adults.
