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Higher body mass index is a significant risk factor for acne formation in schoolchildren

European Journal of Dermatology. Volume 16, Number 3, 251-3, May-June 2006, Investigative report

Summary

Author(s) : Min-Chien Tsai, WenChieh Chen, Yu-Wen Cheng, Cheng-Yu Wang, Guan-Yu Chen, Tzung-Jen Hsu , Department of Dermatology, Chang Gung Memorial Hospital, Kaohsiung, Ta-Pei Road 123, Niao-Sung, 83301 Kaohsiung, Chang Gung University, Taoyuon, Taiwan, Department of Dermatology, Armed Forces Taichung General Hospital, 348, Sec. 2, Chung-Shan Road, Tai-Ping, 411 Taichung, Taiwan, Department of Dermatology, Penghu Hospital, The Department of Health, Chung-Cheng Road 10, Magung, Penghu 880, Taiwan.

Summary : Obesity is frequently accompanied by peripheral hyperandrogenism, which may be associated with increased sebum production and the development of severe acne. Body mass index (BMI) is one of the most accurate ways to measure and determine obesity. The aim of the present study was to study the correlation between obesity and the point prevalence and patterns of acne in schoolchildren. A total of 3,274 children (aged 6-11 years) from Magong Township were examined by two board-certified dermatologists. The acne prevalence was 7.3%, with more girls affected than boys (ratio \= 1.5). Comedones were more commonly observed than inflammatory acne (10.4% vs. 6.9%). The mean of BMI in non-acne students (18.2 ± 3.4) was significantly lower than that in acne subjects (19.5 ± 3.7), without gender difference. Overall schoolchildren with a BMI <\; 18.5 had less prevalence rate of acne, especially the inflammatory lesions, while those with a BMI-for-age ≥ 95% had a significantly higher rate of acne development.

Keywords : acne, body mass index, child

ARTICLE

Auteur(s) : Min-Chien Tsai¹, WenChieh Chen¹, Yu-Wen Cheng¹, Cheng-Yu Wang¹, Guan-Yu Chen², Tzung-Jen Hsu³

¹Department of Dermatology, Chang Gung Memorial Hospital, Kaohsiung, Ta-Pei Road 123, Niao-Sung, 83301 Kaohsiung, Chang Gung University, Taoyuon, Taiwan
²Department of Dermatology, Armed Forces Taichung General Hospital, 348, Sec. 2, Chung-Shan Road, Tai-Ping, 411 Taichung, Taiwan
³Department of Dermatology, Penghu Hospital, The Department of Health, Chung-Cheng Road 10, Magung, Penghu 880, Taiwan

accepté le 3 Janvier 2006

Acne is a common skin disorder affecting 80% of young people between 12 and 18 years of age [1]. It is not until puberty that acne becomes a major problem and acne is often a herald manifestation of puberty [2]. Androgens have long been recognized to stimulate sebaceous glands for the production of sebum, while hyperandrogensim is closely associated with acne formation. On the other hand, obesity is frequently accompanied by peripheral hyperandrogenism, such as in polycystic ovary syndrome [3, 4]. Obesity is an increasingly recognized worldwide problem and the prevalence of childhood obesity is rising rapidly [5]. The body mass index (BMI) is one of the most accurate ways to measure and determine obesity in practice.Penghu is the largest off-shore island of Taiwan, with Magong township being the most populous district. Being a relatively isolated area with little migration of people, especially the elderly and children, Penghu may serve as an ideal place for epidemiological study. The aim of the current study was to understand the acne epidemiology in schoolchildren and the association between BMI and acne development.

Materials and methods

This is a cross-sectional population-based point prevalence study. In total 3,274 children (aged 6-11 years) from four primary schools from urban areas in Magong Township, Penghu County were enrolled in this study and examined by two board-certified dermatologists. Diagnosis of acne was defined by presence of at least 3-5 comedones or at least one inflammatory papulopustule. Recorded were: lesions in the form of comedones, or inflammatory acne like papules, pustules, nodules or cysts. Because of the large number of examinees, only the face and neck were assessed, with the chest and back being excluded. BMI was calculated by dividing the body weight with the square of height (kg/m²). According to the guideline proposed by the World Health Organization, the normal range of BMI is between 18.5 and 24.9, and values below 18.5 imply underweight, while overweight is defined by a BMI over 25 and obesity over 30 kg/m². The BMI values of 568 acne and those of 2,706 non-acne patients were compared and analyzed by using the Statistical Package for Social Science (SPSS Version 10.0). A P-value < 0.05 was considered to be significant. The χ2 test of independence was used to compare the association of acne with gender, age, and BMI, while the association between mean of BMI and acne forms was analyzed by unpaired t test.

Results

Point prevalence of acne

The overall prevalence of acne was 17.3% in the schoolchildren examined, with girls slightly more commonly affected than boys (F/M = 1.5). The prevalence rate increased with age, from 5.7% in low graders at 6-8 years to 28.8% in high graders at 9-11 years. The gender difference also became more obvious in the high graders (F/M = 1.6) than low graders (F/M = 1.3).

Overall, comedone (10.4%) was the more common manifestation of acne than inflammatory lesions (6.9%) at all ages in both genders (10.4% vs. 6.9%), with high rates of inflammatory acne being observed among high graders. The numbers of both comedones and inflammatory lesions escalated suddenly at 10~11 years. No nodulocystic lesions could be found in our series.

Correlation between acne and BMI

The BMI of the boys examined lay between 13.0-36.8 (mean 18.9) and that of the girls 12.1-35.7 (mean 17.9). The mean of BMI is significantly correlated with increasing age (P < 0.001). The mean of BMI in acne children (19.5 ± 3.7) is within normal limits, but significantly higher than that in non-acne persons (18.2 ± 3.4) (P < 0.001). Additionally, in both girls and boys, children with inflammatory acne had a higher BMI (20.7 ± 3.8) than those with only comedones (18.7 ± 3.4) (P < 0.001) (Table 1).

Overweight students with a BMI ≥25 had higher acne prevalence than those with a BMI < 25 (P = 0.02), while underweight students with a BMI < 18.5 showed lower acne prevalence than normal children or those with a BMI ≥ 25 (P < 0.001) (Table 2), irrelevant of the gender difference. Generally, students with BMI < 18.5 developed fewer inflammatory acnes (P < 0.001).

Obese children with a BMI-for-age ≥ 95% had a higher incidence of acne than BMI-for-age between 5th and 85th in both genders (P < 0.001) (Table 3). The girls with acne had 3-fold higher rates of being overweight as compared to boys with acne. Inflammatory acne was more commonly seen in children with a BMI-for-age ≥ 95% (P < 0.001)
Table 1 Means of BMI in non-acne versus acne children

BMI		Boys	Girls	Total
Non-acne		18.8 ± 3.7	17.6 ± 2.9	18.2 ± 3.4
Acne	Total	20.2 ± 4.1	19.4 ± 3.4	19.5 ± 3.7
Comedones only	19.4 ± 3.7	18.8 ± 3.2	18.7 ± 3.4
Inflammatory lesions ± comedones	21.5 ± 4.3	20.3 ± 3.5	20.7 ± 3.8

Table 2 Distribution of BMI (BMI < 18.5, 18.5 ≤ BMI < 25, BMI ≥ 25) and acne

Patient number and percentage (%)	BMI < 18.5		18.5 ≤ BMI < 25		BMI ≥ 25		Total
Gender	Boys	Girls	Boys	Girls	Boys	Girls	Boys	Girls
Non-acne	830 (91)	926 (84)	464 (83)	352 (68)	104 (81)	30 (58)	1398	1308
Acne; Total	86 (9)	172 (16)	97 (17)	166 (32)	25 (19)	22 (42)	208	360
Comedones only	65 (7)	116 (11)	58 (10)	85 (16)	10 (8)	9 (17)	133	210
Inflammatory lesions ± comedones	21 (2)	56 (5)	39 (7)	81 (16)	15 (11)	13 (25)	75	150
Total	916	1098	561	518	129	52	1606	1668

Table 3 Correlation between the distribution of BMI-for-age and acne formation

Patient number and percentage (%)	BMI-for-age < 95%		BMI-for-age ≥ 95%
Gender	Boys	Girls	Boys	Girls
Non-acne	1146 (88)	1198 (80)	252 (81)	110 (62)
Acne; Total	149 (12)	293 (20)	59 (19)	67 (38)
Comedones only	103 (8)	181 (12)	30 (10)	29 (16)
Inflammatory lesions ± comedones	46 (4)	112 (8)	29 (9)	38 (22)
Total	1295	1491	311	177

Discussion

Our study may have the following limitations: 1) definition used to diagnose acne varies diversely in different studies, ranging from “one closed or open comedone” to “more than 20 inflammatory and retentional lesions” [6]; 2) the examination did not include the trunk, accounting for less than 5% of the acne location, which might lead to an underestimation of the prevalence [7, 8].

The overall prevalence of acne in our series reaches 17.3%, with its peak at 36% in 11-year-old girls. The data from schools (including ages 4-7 years) throughout the State of Victoria in Australia was 36.1%, ranging from 27.7% in ages 10-12 years to 93.3% in 16-18 years [9], whereas in Sweden the prevalence at age 12 was 37% in girls compared to 15% in boys [10]. The acne prevalence in schoolchildren aged 5-16 years in rural Ethiopia and Brazil was 2.7% [11, 12]. A previous study in Hong Kong showed a much lower acne prevalence of 1.6% in primary school student groups [13]. The acne prevalence in our prepubertal children at 11 years, with 36% of the girls and 16% of the boys affected, approaches that of western countries [9, 10]. Our study indicates that environmental factors may influence the development of acne in people of the same ethnic group.

Androgens have been recognized to play an essential role in stimulating sebum production and sebum overproduction is among the major pathogenic factors in acne formation [14]. Sebocytes possess all the necessary enzymes to synthesize androgen de novo from cholesterol or to transform weak androgens into more powerful derivatives [15]. The activity of these enzymes is increased in the sebaceous glands of patients with acne [15]. Higher BMI was found to be associated with polycystic ovary syndrome and hyperandrogenism, which may clinically manifest as acne, hirsutism and irregular menstruation [16]. In our study, although the average BMI of students aged 6-11 years with acne (19.5 ± 3.7) is within normal limits, those who are underweight (BMI < 18.5) seem to develop acne less frequently. Moreover, since children’s body fatness changes over years as they grow up and girls differ from boys in their adiposity as they mature, the concept of BMI is used differently in children than in adults. The BMI for children and teenagers (2-20 years of age) is usually adjusted as “BMI-for-age”, which, being gender and age specific, is plotted on gender specific growth charts. Overweight is defined as BMI-for-age ≥ 95th percentile for chronological age, while normal BMI-for-age means the range between 5th and 85th (< 85th) percentile, and BMI-for-age from 85th to < 95th percentile indicates being at risk of overweight. In our series, obese children, regardless of sex, have significantly higher rates of acne formation (P < 0.001). Moreover, the influence of obesity on acne is more obvious in girls, who show 3-fold higher rates of being overweight than boys with acne. However, in a cross-sectional population-based study in 14-17 year old adolescents, there are weak associations between weight loss, low body weight, stress, physical exercise or signs of hyperandrogenism and menstrual cycle patterns [17].

A direct association between obesity and acne, however, seems equivocal in adult women. In female twins (mean age 46 years) there was no significant difference in weight, BMI and height between those with acne and without acne [18]. In women with polycystic ovary syndrome (mean age 24.7 years), a significant difference in acne score did not exist between subjects with BMI < 25 and those with BMI > 30 [19]. In an Italian study on women with acne (age > 17 years), the acne severity was not positively correlated with BMI [20]. Other factors in addition to obesity, such as life style, work stress and hormonal status, which occurs more frequently in adults than in children, are supposed to complicate the situation in adults.

In summary, acne is a common problem in our series, with the prevalence rate approaching that in western countries. Children with a BMI < 18.5 seem to be less predisposed to acne formation, while BMI-for-age ≥ 95% may be a significant risk factor for acne in schoolchildren.

Acknowledgments

We thank Dr. Hsu-Tai Liu, Department of Epidemiology, Johns Hopkins University Medical Institutions, Baltimore Maryland, for his assistance in the statistical analysis in this study.

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