CED
Clinical dermatology • Original article
Clinical and Experimental Dermatology
Epidemiology and risk factors of childhood acne in Korea: a cross-sectional community based study S. Y. Park,1,2 H. H. Kwon,1,2 S. Min,1,2 J. Y. Yoon2 and D. H. Suh1,2 1 Department of Dermatology, Seoul National University Hospital, Seoul, South Korea; and 2Acne and Rosacea Research Laboratory, Seoul National University Hospital, Seoul, South Korea
doi:10.1111/ced.12686
Summary
Background. The epidemiology of acne vulgaris appears to be evolving, with an increasingly earlier onset seen in childhood. Relevant studies have been rarely performed in Asia. Aim. We sought to estimate the prevalence and clinical characteristics of acne among schoolchildren, and its association with treatment-seeking behaviour, body mass index (BMI), nutritional habits and other lifestyle elements. Methods. A cross-sectional study was conducted with elementary schoolchildren aged 7–12 years. Children were interviewed by self-administered questionnaires, and were subsequently evaluated by dermatologists. Results. Of 693 children enrolled, 36.2% were diagnosed with acne, and the prevalence increased with age. Additionally, clinical characteristics including severity, duration of disease and lesion distribution were significantly different between the lower (aged 7–9 years) and the higher (aged 10–12 years) grades. Subjective features including recognition about acne and treatment-seeking behaviours were also different between the two groups. Overweight or obesity (BMI ≥ 25 kg/m2 at 18 years of age; OR = 2.7) and consumption of chocolates/sweets (OR = 1.6) were significant risk factors for acne. Conclusions. In the current study, the prevalence of acne among elementary schoolchildren was high, but only a few children had received treatment. Physicians should be attentive to childhood acne, and educate patients and their parents about the need to treat it.
Introduction Acne vulgaris is a nearly universal cutaneous disease, mainly affecting adolescents and young adults, with a prevalence rate of > 80%.1 Recently, childhood acne has become more common, and there is growing consensus about age groupings in childhood acne.2 Therefore, Correspondence: Professor Dae Hun Suh, Department of Dermatology and Acne and Rosacea Research Laboratory, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul 110-744, South Korea E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. The first two authors contributed equally to this work and should be considered joint first authors. Accepted for publication 6 January 2015
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preadolescent acne without underlying endocrinopathy is now considered a normal variant of acne.3 Based on previous reports, acne carries a significant psychosocial burden not only in the peak age group but also in preadolescent patients.4,5 As acne in childhood may persist over many years, early control may help to minimize its impact on patients over the lifespan of the disease. Recent studies with adult and adolescent patients have reported various factors, including hormones, body mass index (BMI) and diet, to be involved with acne initiation and aggravation.6,7 Although these reports provided valuable information, relevant data for childhood acne have rarely been reported, especially in Asian patients. Investigating communitybased epidemiology, clinical manifestations and risk factors of childhood acne would be useful in estimating
ª 2015 British Association of Dermatologists
Epidemiology and risk factors of childhood acne S. Y. Park et al.
the social costs of acne and establishing educational initiatives for patients and the general public about the treatment and prevention of childhood acne. The aim of this study was to investigate the prevalence, clinical features, recognition, treatment-seeking behaviours and risk factors of childhood acne. To our knowledge, this is the first large-scale study concentrating various aspects of childhood acne in Asia.
We evaluated the interobserver variability for Leeds grade among randomly selected 15 pupils, and found that Cohen j between the two dermatologists was 0.96 (95% CI 0.86–1.06). The height and weight of each student were also measured for calculating BMI. We used the children’s BMI grouping, which defines BMI < 17 kg/m2 as underweight, BMI ≥ 25 kg/m2 as overweight and BMI ≥ 30 kg/m2 as obese at 18 years of age.10,11
Methods Statistical analysis Study design
We performed a cross-sectional study between April and July 2014, after the approval of the ethics committee. This study was performed to identify and evaluate pediatric patients with acne in Korea. As a preliminary, limited-scale study, we randomly selected 2 schools by simple one-stage cluster sampling from the total of 597 elementary schools in Seoul. We visited both schools and enrolled all students in grades 1–6 (aged 7–12 years) whose parents provided informed consent. Questionnaires
Each student was asked questions about factors associated with acne, including the number of hours of sleep, the number of times they washed their face each day, use of moisturizers and their favourite foods. The checklist of favourite foods included meats, fish, instant foods, vegetables and fruits, bread, noodles, milk, cheese, chocolates/sweets, yogurt, snacks, chicken, pizza and ‘other’. Additional questions for children with acne included duration of acne, recognition of having acne and treatment history. Treatment history was classified into five categories: visiting a hospital (including dermatology clinics and general physicians), visiting a pharmacy, using cosmetics, selftreatment (such as self-extraction) and no treatment.
All statistical analyses were performed using the Statistical Package for the Social Sciences (v20; IBM Inc., Armonk, NY, USA) and P < 0.05 was considered statistically significant. The Pearson v² test and Student ttest were used to analyse categorical and continuous variables, respectively. Leeds grading score and acne lesion counts were analysed with the Mann–Whitney U-test. For continuous variables, results are shown as mean SD. We investigated the associations between risk factors and acne by binary logistic regression, and reported as OR and 95% CI. We analysed the data according to age, sex and acne presence. For agespecific analyses, students were categorized into two subgroups: lower (7–9 years old, n = 328) and upper (10–12 years old, n = 365) grades.
Results We enrolled a total of 693 students [352 (50.8%) boys, 341 (49.2%) girls; mean SD age 9.6 1.65) years, range 7–12). Table 1 shows the age distribution of enrolled children. Prevalence and duration of acne
The total prevalence of acne among the children surveyed was 36.2%. The proportion of participants with acne increased with age (Fig. 1), being present in Table 1 Age distribution of enrolled participants.
Clinical assessment
Two board-certified dermatologists (HHK and SM) examined the participants’ skin in the school auditorium using direct daylight. Acne diagnosis was confirmed if there were specific acne lesions including open and closed comedones, papules, pustules and nodules. Dermatologists counted acne lesions, and the severity of acne was assessed on a four-category scale (none, mild, moderate and severe) according to Lehmann et al.8 and the Leeds Revised Acne Grading System.9
ª 2015 British Association of Dermatologists
Boys (n = 352) Age, years* 9.59 1.64 Age distribution, n (%) 7 53 (15.1) 8 44 (12.5) 9 72 (20.5) 10 62 (17.6) 11 68 (19.3) 12 53 (15.1)
Girls (n = 341)
Total (n = 693)
9.66 1.67
9.62 1.65
56 27 76 59 65 58
(16.4) (7.9) (22.3) (17.3) (19.1) (17.0)
109 71 148 121 133 111
(15.7) (10.2) (21.4) (17.5) (19.2) (16.0)
*Mean SD.
Clinical and Experimental Dermatology (2015) 40, pp844–850
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Epidemiology and risk factors of childhood acne S. Y. Park et al.
Severity, lesion count and distribution of acne
(a)
Of the 251 children with acne, 237 (94.4%) had mild and 14 (5.6%) had moderate acne. Moderate acne was present in 1.3% of students in the lower and 7.5% of students in the upper grades (P = 0.04). The mean severity score according to the Leeds revised acne grading was 1.0 0.52, and was higher in the upper than the lower grades (1.0 0.59 vs. 0.9 0.27; P = 0.03). The acne lesions were counted and categorized as noninflammatory (closed and open comedones) or inflammatory (papules, nodules and pustules) lesions. For the lower and upper grades, respectively, mean noninflammatory lesion counts were 1.6 4.57 and 5.8 11.83 (P < 0.001), mean inflammatory lesion counts were 0.1 0.47 and 1.4 4.25 (P < 0.001) and total counts of acne lesions were 1.7 4.66 and 7.2 14.41 (P < 0.01). The number of lesions was stratified into four groups: 1–5, 6–10, 11–20 and > 20 lesions. Figure 2a shows the comparison of lesion counts between both subgroups. We also investigated the distribution of lesions. The cheek was the most involved site (77.7%), followed by the forehead (44.6%) and the nose (29.9%). We observed significant differences in lesion distribution between the upper and lower grades. Cheek lesions were more prevalent in the lower grades, and forehead and nose lesions were more prevalent in the upper grades (P < 0.01, P < 0.001 and P = 0.03, respectively; Fig. 2b).
(b)
Figure 1 Prevalence of acne at each age. The prevalence of acne
increased with age. There were no significant differences between boys and girs in any of the age groups (all P-values > 0.05). Acne was diagnosed in 47.4% of students in the upper and 23.8% of students in the lower grades (*P < 0.001).
47.4% of children in the upper grades and in 23.8% of children in the lower grades (P < 0.001; Fig. 1). Overall, more girls than boys were diagnosed with acne (37.8% vs. 34.7%). Acne was more prevalent in girls than in boys in both the upper (50.0% vs. 44.8%) and the lower (23.9% vs. 23.7%) grades. The difference in prevalence between both sexes was smaller in the lower grades, which suggests a tendency toward a female predominance with increasing age. However, we observed no significant differences between the sexes in total acne prevalence, prevalence at each age, or prevalence in the lower or upper grades (all the P > 0.05). The mean duration of acne was 0.7 years in the total group, 0.5 years in the lower grades and 0.8 years in the upper grades (P = 0.04).
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Recognition of acne and treatment-seeking behaviour
Overall, 39.4% of 251 students with acne recognized that they had the condition, with the proportions being higher in the upper than the lower grades (49.1% vs. 17.9%; P < 0.001). Most elementary schoolchildren with acne had received no treatment, and only 6% (n = 15) had visited hospitals for acne treatment. A few students had visited a pharmacy (n = 4), used cosmetics (n = 4) or performed selftreatment (n = 1). None of the students with acne in the lower grades had received any treatment.
Association of acne with possible risk factors
Overweight or obese students (BMI ≥ 25 kg/m2 at 18 years of age) had a higher prevalence of acne (ageand sex-adjusted OR = 2.7; 95% CI 1.81–3.92) than normal or underweight students (BMI < 25 kg/m2 at 18 years of age). Students without acne had longer
ª 2015 British Association of Dermatologists
Epidemiology and risk factors of childhood acne S. Y. Park et al.
(a)
(b)
Figure 2 Clinical features of childhood
acne. (a) The number of lesions was stratified into four groups: 1–5, 6–10, 11–20 and > 20 lesions. Non-inflammatory lesions were dominant in childhood acne and lesion counts were higher in the upper grades than in the lower grades. (b) Cheek lesions were more prevalent in the lower and lesions on the forehead and nose were more prevalent in the upper grades (*P < 0.01, P < 0.001 and P < 0.05, respectively)
sleep duration than those with acne (9.0 vs. 8.7 h; P < 0.01). Sleeping < 9 h was positively associated with an increased risk for acne (OR = 2.0; 95% CI
ª 2015 British Association of Dermatologists
1.48–2.79), but after adjusting for age, no significant difference was observed (age-adjusted OR = 1.4; 95% CI 0.96–1.93). No association was observed between
Clinical and Experimental Dermatology (2015) 40, pp844–850
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Epidemiology and risk factors of childhood acne S. Y. Park et al.
moisturizer use and acne prevalence (OR = 1.1; 95% CI 0.77–1.61), and there was no significant difference in the number of facial washings between the students with and without acne (2.5 vs. 2.4; P = 0.29). The proportions of favourite foods among students with and without acne are shown in Fig. 3. Students favouring meats, chocolates/sweets and pizza had a higher prevalence of acne (OR = 1.5, 1.7 and 1.4; 95% CI 1.09–2.14, 1.24–2.39 and 1.03–1.95, respectively) than those not favouring these foods. However, after adjusting for age, only chocolates/sweets (ageadjusted OR = 1.6; CI 1.13–2.24) maintained a significant difference, whereas meats and pizza did not (ageadjusted OR = 1.4 and 1.3; 95% CI 0.96–1.93 and 0.97–1.87, respectively).
Discussion Our results confirm that acne is a common skin disease, even in preadolescents. Our findings are consistent with those of previous studies reporting that acne prevalence in schoolchildren tends to increase with age.6,12 Tan et al.13 found that the severity of acne increased with age in adolescents, and Silverberg et al.14 reported that the prevalence of severe acne dramatically increased after the age of 11 years. We observed differences in acne severity between the lower and upper grades. Taken together with previous results, our findings indicate that the severity of acne may begin increasing during the upper grades of elementary school in Korea. The earliest sign of pubertal maturation may be the appearance of acne.15 Because the age of puberty onset is currently earlier than in the past, the age of first acne
appearance is decreasing and acne also begins slightly earlier in females than in males.12 Our results showed that acne was more prevalent in girls in the upper grades, which agrees with results of previous studies.6,12 In our study, older children had higher acne severity and more acne lesions, with a notable increase in inflammatory lesions compared with younger children. Additionally, younger children had lesions mainly on their cheeks, whereas older children had a wider distribution on the face. These results reflect the natural course of acne, which usually starts with predominantly noninflammatory lesions, followed by an increase in inflammatory lesions and a wider distribution of involved areas. Starting proper treatment in a timely manner when acne is in its early stages and is localized to the cheeks can prevent the progression into more severe and widely distributed stages. The children in our study had poor recognition of acne and showed inadequate treatment-seeking behaviours. This is probably because most of them were unaware of the presence of acne and, although some of them recognized it, they may not have recognized acne as a disease. In fact, many people, especially in Asian countries, believe that acne is not a medical condition requiring treatment but, rather, a natural part of growing up.16 Approximately one-third of the children who had used some type of treatment depended on a pharmacy visit, cosmetics or self-treatment instead of visiting a hospital. A previous study reported similar behaviour patterns in patients with acne.17 The results of our study support the positive associations between BMI and acne development.6,18,19 Increased BMI may be associated with hyperandrogenism
Figure 3 Favourite foods of students with
and without acne. A higher proportion of students with acne favoured meats, instant foods, bread, chocolates/sweets, yogurt, chicken and pizza than did patients without acne. A higher proportion of participants without acne favoured vegetables and fruits than did those with acne.
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ª 2015 British Association of Dermatologists
Epidemiology and risk factors of childhood acne S. Y. Park et al.
and a high glycaemic load (GL) diet.2,20 A high GL diet can induce hyperinsulinaemia, which causes a hormonal cascade, resulting in androgen-induced sebum production and keratinocyte proliferation, which leads to the development of acne.21,22 Actually, in one study, a low GL diet induced acne improvement.23 Among the patients’ nutritional habits, chocolate/ sweets was the only factor associated with an increased prevalence of acne in our study. In a previous study in Korea, chocolate was an aggravating factor for 19% of patients with acne.24 Interestingly, childhood acne shares risk factors with acne later in life. There are several limitations to this study. First, important clinical issues around acne, including family history and psychosocial burden of disease were not investigated. Second, physical examination of acne scars, which are permanent sequeale of acne, might have produced more interesting data. Finally, application of sophisticated criteria for BMI and enrolment of more patients on a nationwide scale should be performed in future studies.
Conclusion Prevalence of acne among elementary schoolchildren in this study was relatively high, with distinct characteristic features distinguishing between the upper and lower grades, while few children had received treatment. We strongly believe that this report could be used to establish a public health plan for acne prevention and treatment. Physicians should be attentive to childhood acne and educate patients about it.
What’s already known about this topic? • Although the epidemiology of acne vulgaris
had been evolving over recent years, with an increasingly earlier onset seen in childhood, relevant studies have been rarely performed in Asia.
What does this study add? • The prevalence of acne among elementary
school children was high, while only a few children had received treatment. • Overweight/obesity and consumption of chocolates/sweets were significant risk factors of acne.
ª 2015 British Association of Dermatologists
References 1 Goodman G. Acne–natural history, facts and myths. Aust Fam Physician 2006; 35: 613–6. 2 Goldberg JL, Dabade TS, Davis SA et al. Changing age of acne vulgaris visits: another sign of earlier puberty? Pediatr Dermatol 2011; 28: 645–8. 3 Mancini AJ, Baldwin HE, Eichenfield LF et al. Acne life cycle: the spectrum of pediatric disease. Semin Cutan Med Surg 2011; 30: S2–5. 4 Koo J. The psychosocial impact of acne: patients’ perceptions. J Am Acad Dermatol 1995; 32: S26–30. 5 Tasoula E, Gregoriou S, Chalikias J et al. The impact of acne vulgaris on quality of life and psychic health in young adolescents in Greece. Results of a population survey. An Bras Dermatol 2012; 87: 862–9. 6 Karciauskiene J, Valiukeviciene S, Gollnick H et al. The prevalence and risk factors of adolescent acne among schoolchildren in Lithuania: a cross-sectional study. J Eur Acad Dermatol Venereol 2014; 28: 733–40. 7 Bagatin E, Timpano DL, Guadanhim LR et al. Acne vulgaris: prevalence and clinical forms in adolescents from Sao Paulo, Brazil. An Bras Dermatol 2014; 89: 428–35. 8 Lehmann HP, Robinson KA, Andrews JS et al. Acne therapy: a methodologic review. J Am Acad Dermatol 2002; 47: 231–40. 9 O’Brien SC, Lewis JB, Cunliffe WJ. The Leeds revised acne grading system. J Dermatolog Treat 1998; 9: 215–20. 10 Cole TJ, Flegal KM, Nicholls D et al. Body mass index cut offs to define thinness in children and adolescents: international survey. BMJ 2007; 335: 194. 11 Cole TJ, Bellizzi MC, Flegal KM et al. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000; 320: 1240–3. 12 Kilkenny M, Merlin K, Plunkett A et al. The prevalence of common skin conditions in Aust school students: 3. acne vulgaris. Br J Dermatol 1998; 139: 840–5. 13 Tan HH, Tan AW, Barkham T et al. Community-based study of acne vulgaris in adolescents in Singapore. Br J Dermatol 2007; 157: 547–51. 14 Silverberg JI, Silverberg NB. Epidemiology and extracutaneous comorbidities of severe acne in adolescence: a U.S. population-based study. Br J Dermatol 2014; 170: 1136–42. 15 Cantatore-Francis JL, Glick SA. Childhood acne: evaluation and management. Dermatol Ther 2006; 19: 202–9. 16 Abad-Casintahan F, Chow SK, Goh CL et al. Toward evidence-based practice in acne: consensus of an Asian Working Group. J Dermatol 2011; 38: 1041–8. 17 Suh DH, Shin JW, Min SU et al. Treatment-seeking behaviors and related epidemiological features in Korean acne patients. J Korean Med Sci 2008; 23: 969–74. 18 Tsai MC, Chen W, Cheng YW et al. Higher body mass index is a significant risk factor for acne formation in schoolchildren. Eur J Dermatol 2006; 16: 251–3.
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19 Hogewoning AA, Koelemij I, Amoah AS et al. Prevalence and risk factors of inflammatory acne vulgaris in rural and urban Ghanaian schoolchildren. Br J Dermatol 2009; 161: 475–7. 20 Smith RN, Mann NJ, Braue A et al. The effect of a highprotein, low glycemic-load diet versus a conventional, high glycemic-load diet on biochemical parameters associated with acne vulgaris: a randomized, investigator-masked, controlled trial. J Am Acad Dermatol 2007; 57: 247–56. 21 Deplewski D, Rosenfield RL. Role of hormones in pilosebaceous unit development. Endocr Rev 2000; 21: 363–92.
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22 Cappel M, Mauger D, Thiboutot D. Correlation between serum levels of insulin-like growth factor 1, dehydroepiandrosterone sulfate, and dihydrotestosterone and acne lesion counts in adult women. Arch Dermatol 2005; 141: 333–8. 23 Kwon HH, Yoon JY, Hong JS et al. Clinical and histological effect of a low glycaemic load diet in treatment of acne vulgaris in Korean patients: a randomized, controlled trial. Acta Derm Venereol 2012; 92: 241–6. 24 Suh DH, Kim BY, Min SU et al. A multicenter epidemiological study of acne vulgaris in Korea. Int J Dermatol 2011; 50: 673–81.
ª 2015 British Association of Dermatologists
Clinical dermatology • Original article
Clinical and Experimental Dermatology
Epidemiology and risk factors of childhood acne in Korea: a cross-sectional community based study S. Y. Park,1,2 H. H. Kwon,1,2 S. Min,1,2 J. Y. Yoon2 and D. H. Suh1,2 1 Department of Dermatology, Seoul National University Hospital, Seoul, South Korea; and 2Acne and Rosacea Research Laboratory, Seoul National University Hospital, Seoul, South Korea
doi:10.1111/ced.12686
Summary
Background. The epidemiology of acne vulgaris appears to be evolving, with an increasingly earlier onset seen in childhood. Relevant studies have been rarely performed in Asia. Aim. We sought to estimate the prevalence and clinical characteristics of acne among schoolchildren, and its association with treatment-seeking behaviour, body mass index (BMI), nutritional habits and other lifestyle elements. Methods. A cross-sectional study was conducted with elementary schoolchildren aged 7–12 years. Children were interviewed by self-administered questionnaires, and were subsequently evaluated by dermatologists. Results. Of 693 children enrolled, 36.2% were diagnosed with acne, and the prevalence increased with age. Additionally, clinical characteristics including severity, duration of disease and lesion distribution were significantly different between the lower (aged 7–9 years) and the higher (aged 10–12 years) grades. Subjective features including recognition about acne and treatment-seeking behaviours were also different between the two groups. Overweight or obesity (BMI ≥ 25 kg/m2 at 18 years of age; OR = 2.7) and consumption of chocolates/sweets (OR = 1.6) were significant risk factors for acne. Conclusions. In the current study, the prevalence of acne among elementary schoolchildren was high, but only a few children had received treatment. Physicians should be attentive to childhood acne, and educate patients and their parents about the need to treat it.
Introduction Acne vulgaris is a nearly universal cutaneous disease, mainly affecting adolescents and young adults, with a prevalence rate of > 80%.1 Recently, childhood acne has become more common, and there is growing consensus about age groupings in childhood acne.2 Therefore, Correspondence: Professor Dae Hun Suh, Department of Dermatology and Acne and Rosacea Research Laboratory, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul 110-744, South Korea E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. The first two authors contributed equally to this work and should be considered joint first authors. Accepted for publication 6 January 2015
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Clinical and Experimental Dermatology (2015) 40, pp844–850
preadolescent acne without underlying endocrinopathy is now considered a normal variant of acne.3 Based on previous reports, acne carries a significant psychosocial burden not only in the peak age group but also in preadolescent patients.4,5 As acne in childhood may persist over many years, early control may help to minimize its impact on patients over the lifespan of the disease. Recent studies with adult and adolescent patients have reported various factors, including hormones, body mass index (BMI) and diet, to be involved with acne initiation and aggravation.6,7 Although these reports provided valuable information, relevant data for childhood acne have rarely been reported, especially in Asian patients. Investigating communitybased epidemiology, clinical manifestations and risk factors of childhood acne would be useful in estimating
ª 2015 British Association of Dermatologists
Epidemiology and risk factors of childhood acne S. Y. Park et al.
the social costs of acne and establishing educational initiatives for patients and the general public about the treatment and prevention of childhood acne. The aim of this study was to investigate the prevalence, clinical features, recognition, treatment-seeking behaviours and risk factors of childhood acne. To our knowledge, this is the first large-scale study concentrating various aspects of childhood acne in Asia.
We evaluated the interobserver variability for Leeds grade among randomly selected 15 pupils, and found that Cohen j between the two dermatologists was 0.96 (95% CI 0.86–1.06). The height and weight of each student were also measured for calculating BMI. We used the children’s BMI grouping, which defines BMI < 17 kg/m2 as underweight, BMI ≥ 25 kg/m2 as overweight and BMI ≥ 30 kg/m2 as obese at 18 years of age.10,11
Methods Statistical analysis Study design
We performed a cross-sectional study between April and July 2014, after the approval of the ethics committee. This study was performed to identify and evaluate pediatric patients with acne in Korea. As a preliminary, limited-scale study, we randomly selected 2 schools by simple one-stage cluster sampling from the total of 597 elementary schools in Seoul. We visited both schools and enrolled all students in grades 1–6 (aged 7–12 years) whose parents provided informed consent. Questionnaires
Each student was asked questions about factors associated with acne, including the number of hours of sleep, the number of times they washed their face each day, use of moisturizers and their favourite foods. The checklist of favourite foods included meats, fish, instant foods, vegetables and fruits, bread, noodles, milk, cheese, chocolates/sweets, yogurt, snacks, chicken, pizza and ‘other’. Additional questions for children with acne included duration of acne, recognition of having acne and treatment history. Treatment history was classified into five categories: visiting a hospital (including dermatology clinics and general physicians), visiting a pharmacy, using cosmetics, selftreatment (such as self-extraction) and no treatment.
All statistical analyses were performed using the Statistical Package for the Social Sciences (v20; IBM Inc., Armonk, NY, USA) and P < 0.05 was considered statistically significant. The Pearson v² test and Student ttest were used to analyse categorical and continuous variables, respectively. Leeds grading score and acne lesion counts were analysed with the Mann–Whitney U-test. For continuous variables, results are shown as mean SD. We investigated the associations between risk factors and acne by binary logistic regression, and reported as OR and 95% CI. We analysed the data according to age, sex and acne presence. For agespecific analyses, students were categorized into two subgroups: lower (7–9 years old, n = 328) and upper (10–12 years old, n = 365) grades.
Results We enrolled a total of 693 students [352 (50.8%) boys, 341 (49.2%) girls; mean SD age 9.6 1.65) years, range 7–12). Table 1 shows the age distribution of enrolled children. Prevalence and duration of acne
The total prevalence of acne among the children surveyed was 36.2%. The proportion of participants with acne increased with age (Fig. 1), being present in Table 1 Age distribution of enrolled participants.
Clinical assessment
Two board-certified dermatologists (HHK and SM) examined the participants’ skin in the school auditorium using direct daylight. Acne diagnosis was confirmed if there were specific acne lesions including open and closed comedones, papules, pustules and nodules. Dermatologists counted acne lesions, and the severity of acne was assessed on a four-category scale (none, mild, moderate and severe) according to Lehmann et al.8 and the Leeds Revised Acne Grading System.9
ª 2015 British Association of Dermatologists
Boys (n = 352) Age, years* 9.59 1.64 Age distribution, n (%) 7 53 (15.1) 8 44 (12.5) 9 72 (20.5) 10 62 (17.6) 11 68 (19.3) 12 53 (15.1)
Girls (n = 341)
Total (n = 693)
9.66 1.67
9.62 1.65
56 27 76 59 65 58
(16.4) (7.9) (22.3) (17.3) (19.1) (17.0)
109 71 148 121 133 111
(15.7) (10.2) (21.4) (17.5) (19.2) (16.0)
*Mean SD.
Clinical and Experimental Dermatology (2015) 40, pp844–850
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Epidemiology and risk factors of childhood acne S. Y. Park et al.
Severity, lesion count and distribution of acne
(a)
Of the 251 children with acne, 237 (94.4%) had mild and 14 (5.6%) had moderate acne. Moderate acne was present in 1.3% of students in the lower and 7.5% of students in the upper grades (P = 0.04). The mean severity score according to the Leeds revised acne grading was 1.0 0.52, and was higher in the upper than the lower grades (1.0 0.59 vs. 0.9 0.27; P = 0.03). The acne lesions were counted and categorized as noninflammatory (closed and open comedones) or inflammatory (papules, nodules and pustules) lesions. For the lower and upper grades, respectively, mean noninflammatory lesion counts were 1.6 4.57 and 5.8 11.83 (P < 0.001), mean inflammatory lesion counts were 0.1 0.47 and 1.4 4.25 (P < 0.001) and total counts of acne lesions were 1.7 4.66 and 7.2 14.41 (P < 0.01). The number of lesions was stratified into four groups: 1–5, 6–10, 11–20 and > 20 lesions. Figure 2a shows the comparison of lesion counts between both subgroups. We also investigated the distribution of lesions. The cheek was the most involved site (77.7%), followed by the forehead (44.6%) and the nose (29.9%). We observed significant differences in lesion distribution between the upper and lower grades. Cheek lesions were more prevalent in the lower grades, and forehead and nose lesions were more prevalent in the upper grades (P < 0.01, P < 0.001 and P = 0.03, respectively; Fig. 2b).
(b)
Figure 1 Prevalence of acne at each age. The prevalence of acne
increased with age. There were no significant differences between boys and girs in any of the age groups (all P-values > 0.05). Acne was diagnosed in 47.4% of students in the upper and 23.8% of students in the lower grades (*P < 0.001).
47.4% of children in the upper grades and in 23.8% of children in the lower grades (P < 0.001; Fig. 1). Overall, more girls than boys were diagnosed with acne (37.8% vs. 34.7%). Acne was more prevalent in girls than in boys in both the upper (50.0% vs. 44.8%) and the lower (23.9% vs. 23.7%) grades. The difference in prevalence between both sexes was smaller in the lower grades, which suggests a tendency toward a female predominance with increasing age. However, we observed no significant differences between the sexes in total acne prevalence, prevalence at each age, or prevalence in the lower or upper grades (all the P > 0.05). The mean duration of acne was 0.7 years in the total group, 0.5 years in the lower grades and 0.8 years in the upper grades (P = 0.04).
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Recognition of acne and treatment-seeking behaviour
Overall, 39.4% of 251 students with acne recognized that they had the condition, with the proportions being higher in the upper than the lower grades (49.1% vs. 17.9%; P < 0.001). Most elementary schoolchildren with acne had received no treatment, and only 6% (n = 15) had visited hospitals for acne treatment. A few students had visited a pharmacy (n = 4), used cosmetics (n = 4) or performed selftreatment (n = 1). None of the students with acne in the lower grades had received any treatment.
Association of acne with possible risk factors
Overweight or obese students (BMI ≥ 25 kg/m2 at 18 years of age) had a higher prevalence of acne (ageand sex-adjusted OR = 2.7; 95% CI 1.81–3.92) than normal or underweight students (BMI < 25 kg/m2 at 18 years of age). Students without acne had longer
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Epidemiology and risk factors of childhood acne S. Y. Park et al.
(a)
(b)
Figure 2 Clinical features of childhood
acne. (a) The number of lesions was stratified into four groups: 1–5, 6–10, 11–20 and > 20 lesions. Non-inflammatory lesions were dominant in childhood acne and lesion counts were higher in the upper grades than in the lower grades. (b) Cheek lesions were more prevalent in the lower and lesions on the forehead and nose were more prevalent in the upper grades (*P < 0.01, P < 0.001 and P < 0.05, respectively)
sleep duration than those with acne (9.0 vs. 8.7 h; P < 0.01). Sleeping < 9 h was positively associated with an increased risk for acne (OR = 2.0; 95% CI
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1.48–2.79), but after adjusting for age, no significant difference was observed (age-adjusted OR = 1.4; 95% CI 0.96–1.93). No association was observed between
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moisturizer use and acne prevalence (OR = 1.1; 95% CI 0.77–1.61), and there was no significant difference in the number of facial washings between the students with and without acne (2.5 vs. 2.4; P = 0.29). The proportions of favourite foods among students with and without acne are shown in Fig. 3. Students favouring meats, chocolates/sweets and pizza had a higher prevalence of acne (OR = 1.5, 1.7 and 1.4; 95% CI 1.09–2.14, 1.24–2.39 and 1.03–1.95, respectively) than those not favouring these foods. However, after adjusting for age, only chocolates/sweets (ageadjusted OR = 1.6; CI 1.13–2.24) maintained a significant difference, whereas meats and pizza did not (ageadjusted OR = 1.4 and 1.3; 95% CI 0.96–1.93 and 0.97–1.87, respectively).
Discussion Our results confirm that acne is a common skin disease, even in preadolescents. Our findings are consistent with those of previous studies reporting that acne prevalence in schoolchildren tends to increase with age.6,12 Tan et al.13 found that the severity of acne increased with age in adolescents, and Silverberg et al.14 reported that the prevalence of severe acne dramatically increased after the age of 11 years. We observed differences in acne severity between the lower and upper grades. Taken together with previous results, our findings indicate that the severity of acne may begin increasing during the upper grades of elementary school in Korea. The earliest sign of pubertal maturation may be the appearance of acne.15 Because the age of puberty onset is currently earlier than in the past, the age of first acne
appearance is decreasing and acne also begins slightly earlier in females than in males.12 Our results showed that acne was more prevalent in girls in the upper grades, which agrees with results of previous studies.6,12 In our study, older children had higher acne severity and more acne lesions, with a notable increase in inflammatory lesions compared with younger children. Additionally, younger children had lesions mainly on their cheeks, whereas older children had a wider distribution on the face. These results reflect the natural course of acne, which usually starts with predominantly noninflammatory lesions, followed by an increase in inflammatory lesions and a wider distribution of involved areas. Starting proper treatment in a timely manner when acne is in its early stages and is localized to the cheeks can prevent the progression into more severe and widely distributed stages. The children in our study had poor recognition of acne and showed inadequate treatment-seeking behaviours. This is probably because most of them were unaware of the presence of acne and, although some of them recognized it, they may not have recognized acne as a disease. In fact, many people, especially in Asian countries, believe that acne is not a medical condition requiring treatment but, rather, a natural part of growing up.16 Approximately one-third of the children who had used some type of treatment depended on a pharmacy visit, cosmetics or self-treatment instead of visiting a hospital. A previous study reported similar behaviour patterns in patients with acne.17 The results of our study support the positive associations between BMI and acne development.6,18,19 Increased BMI may be associated with hyperandrogenism
Figure 3 Favourite foods of students with
and without acne. A higher proportion of students with acne favoured meats, instant foods, bread, chocolates/sweets, yogurt, chicken and pizza than did patients without acne. A higher proportion of participants without acne favoured vegetables and fruits than did those with acne.
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Epidemiology and risk factors of childhood acne S. Y. Park et al.
and a high glycaemic load (GL) diet.2,20 A high GL diet can induce hyperinsulinaemia, which causes a hormonal cascade, resulting in androgen-induced sebum production and keratinocyte proliferation, which leads to the development of acne.21,22 Actually, in one study, a low GL diet induced acne improvement.23 Among the patients’ nutritional habits, chocolate/ sweets was the only factor associated with an increased prevalence of acne in our study. In a previous study in Korea, chocolate was an aggravating factor for 19% of patients with acne.24 Interestingly, childhood acne shares risk factors with acne later in life. There are several limitations to this study. First, important clinical issues around acne, including family history and psychosocial burden of disease were not investigated. Second, physical examination of acne scars, which are permanent sequeale of acne, might have produced more interesting data. Finally, application of sophisticated criteria for BMI and enrolment of more patients on a nationwide scale should be performed in future studies.
Conclusion Prevalence of acne among elementary schoolchildren in this study was relatively high, with distinct characteristic features distinguishing between the upper and lower grades, while few children had received treatment. We strongly believe that this report could be used to establish a public health plan for acne prevention and treatment. Physicians should be attentive to childhood acne and educate patients about it.
What’s already known about this topic? • Although the epidemiology of acne vulgaris
had been evolving over recent years, with an increasingly earlier onset seen in childhood, relevant studies have been rarely performed in Asia.
What does this study add? • The prevalence of acne among elementary
school children was high, while only a few children had received treatment. • Overweight/obesity and consumption of chocolates/sweets were significant risk factors of acne.
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