Epidemiology of Acne

Acne vulgaris is a distressing condition related to the pilo sebaceous follicle and which is considered as an ‘adolescent’ disorder. It is characterized by spontaneous resolution in the late teens or early twenties in the majority of cases.The first publication about the epidemiology of acne was in 1931 by Bloch [1]. Already at this time, the onset of acne was noted slightly earlier in girls (12.1 ± 1.5) compared to boys (12.8 ± 1.7 years), retentional lesions being the earliest lesions (13% at 6 years and 32% at 7 years of age).Since this publication, no significant evolution has been noted concerning the age of onset of acne. According to different studies of the literature performed in different countries in the world, the mean onset of acne is 11 years in girls and 12 years in boys, remaining earlier in girls (1 or 2 years) with mainly retentional lesions (open and closed comedones). However, adult acne has also been described recently.The evaluation of the prevalence of adolescent acne is submitted to important variations directly related to the definition of ‘acne’ used in different studies, which is very variable. Indeed, in some studies one closed or opened comedone is sufficient to consider the subject as a ‘patient with acne’ and in other studies such as the Daniel study [2], more than 20 inflammatory and retentional lesions were necessary to consider the subject as having acne. Thus, in Bloch’s study [1], realized among 4,191 subjects and in which one comedone was sufficient to classify the patient as having acne, the prevalence of acne was 68.5% in boys and 59.6% in girls. On the contrary, in Daniel’s study [2], performed in 914 patients, only 27.9% of the boys and 20.8% of the girls had acne lesions. Review of different studies in the literature shows a mean prevalence of between 70 and 87% without significant differences according to country.Two main factors have to be considered:AgeThe frequency of acne in the population increases with age. Thus, among 409 patients (munroe-Ashman) only 22% of subjects had acne lesions at 13 years compared with 68% at 16 years of age.SexCombined with age, gender is an important factor modulating the frequency of acne lesions. Thus, Rademaker et al. [3]have shown that among the girls 61% had acne lesions at 12 years and 83% at 16 years with a maximum between 15 and 17 years. Among the boys, the prevalence of acne was only 40% at 12 years but increased to 95% at 16 years with a maximum of frequency between 17 and 19 years.Two main factors have to be considered:GeneticPrevious history of acne in the family and more specifically in the father or mother increases the risk of acne in children. Thus, in an epidemiological study performed in French schools [2]among 913 adolescents between 11 and 18 years of age, in the group of acne patients, history of acne in the father was noted in 16 vs. 8% in the group without acne lesions. In a similar manner, a history of acne lesions in the mother was noted in 25% of subjects in the acne group vs. 14% in the group without acne lesions, and finally 68% of brothers or sisters had acne in the acne group vs. 57% in the group without acne lesions. Moreover, family history of acne lesions in the father and mother is more often associated with severe acne or acne that responds less to acne treatment with agents such as cyclines [4].Early Onset of Acne LesionsAcne lesions beginning before puberty increases the risk of severe acne and often isotretinoin is necessary to obtain control of the acne lesions. At the beginning, retentional lesions are predominant [5].Cigarette SmokingA recent study indicates that acne is more frequent in smokers [6]. This work has been performed among 891 citizens in Hamburg (age 1–87 years; median: 42). The maximum frequency of acne lesions was noted between 14 and 29 years. 24.2% of the population were active smokers and among them 40.8% had acne lesions. 25% were ex-smokers and among them 23.5% had acne lesions, and finally among the 50.8% of non-smokers acne lesions were identified in only 23.5%. The maximum risk of acne is obtained by the association of three factors: active smoker + male + young subject.Skin ColorAn evaluation of the difference in acne according to skin color has been performed at the Skin Color Center in New York. This study has been performed among 313 patients with acne vulgaris [7]. Thus, the mean age of acne onset appears lower in Hispanic (15.9 years old) compared to Black (20.3 years old) and Asian (18.9 years old) subjects. The frequency of acne at teenage is the highest in Hispanic (79.2%) and similar in Black (59.9%) and Asian (63.2%) groups. Scarring is clearly more frequent in Hispanics (21.8%), remaining low in Blacks (5.9%) with an intermediate frequency in Asians (10.5%). The results are similar concerning severe acne with nodular and cystic lesions: Hispanic 25.5%, Black 18%, Asian 10.5%.Oral ContraceptivesA recent study performed in Sweden [8]described the prevalence rate of acne among adolescents with allergic disease and studied the possible influence of oral contraceptives and tobacco smoking on disease prevalence. Among 186 subjects (15–22 years old) the prevalence of acne was 40.5% for males and 23.8% for females. The use of oral contraceptives was associated with a significantly lower prevalence of acne (yes 14.8%, no 32%; p = 0.038). However, in this study an increase of acne related to smoking is not found as in the previous study [6].In summary, the frequency of adolescent acne in the population appears essentially dependent on age and to a minor degree on sex and skin color. An early onset of lesions and the notion of familial acne are two factors of bad prognosis.There are few studies about the prevalence and specificities of facial acne in the adult population. Several studies have been reported recently:In England [9], 749 employees of a hospital, a university and a large manufacturing firm in Leeds, older than 25 years, were examined. Facial acne was recorded in 231 women and 130 men giving an overall prevalence of 54% in women and 40% in men. It was mainly ‘physiological acne’ but clinical acne (grade >0.75 on the Leeds scale) was recorded in 12% of the women and 3% of the men. Only 1% of the subjects with clinical acne had sought treatment. The majority believed that there was no effective therapy for acne.In Australia [10], 1,457 subjects from central Victoria aged ≥20 years were examined. The prevalence of acne was 12.8% (13.6% for women and 11.8% for men). There was a clear decrease with age from 42% in the age group 20–29 years to 1.4% in the 60–69 age group. Acne was classified as mild in 81.2%, moderate in 17% and severe in 1.8%. Less than 20% were using a treatment on the advice of a medical practitioner.Two recent studies have demonstrated some specific features of acne in adult women:–A postal survey was sent to 173 adult pre-menopausal women treated for acne between 1988 and 1996 in the USA [11]. 91 (52%) answered; all of them had received spironolactone at some point during the course of their treatment. The mean duration of acne was 20.4 years. Acne was reported to be persistent in 80% of the women and 58% of them had an ongoing need for treatment. In this selected population, acne in adult women was particularly persistent and desperately recurring.–Another survey investigated the effect of the menstrual cycle on acne [12]in 400 women aged 12–52 years: 44% had premenstrual flare. Women older than 33 years had a 53% rate of premenstrual flare. The above-mentioned study [11]noted a premenstrual flare in 83% of the adult women with acne.We have conducted an epidemiological study of acne in adult females in France [13]. A self-administered questionnaire was sent to 4,000 adult women aged 25–40 years representative of the French population. Three dermatologists validated the questionnaire. A definition of acne severity, according to questionnaire answers was established before the questionnaire was sent out: ‘clinical acne’ was defined as ≥5 pustules or papulonodules on the face at the date of the questionnaire or during the previous 3 months. ‘Physiological acne’ was defined as 1–4 papulonodules or pustules at the date of the questionnaire or during the previous 3 months.A total of 3,394 women completed the questionnaire of which 3,305 were useable. Prevalence of acne was 41% in adult women. In 17% of the cases, it was ‘clinical acne’ – with 6.2 inflammatory lesions as a mean – and in 24% ‘physiological acne’ – with 1.3 inflammatory acne lesions as a mean. 97% and 94%, respectively, admitted that they used to scratch or squeeze their ‘pimples’. 49% of women with ‘clinical acne’ had acne sequelae, i.e. scars and/or pigmented macules. 34% of women with ‘clinical acne’ had not experienced acne during their adolescence. A premenstrual flare was recorded in 78% of women with ‘clinical acne’. The adult females with acne reported a significantly more oily or mixed type than the non-acne group, sensitive skin was slightly more prevalent in the acne (71%) and physiologic acne group (68%) than in the non-acne group (64%). The sensitivity of the skin to sun was no different among the 3 groups. Smoking, stressful life-style and professional occupation were not different among the three groups. Some differences were recorded between the acne group and the non-acne group for poor sleep (35/32%), drug intake, especially benzodiazepine (10/8%), and daily skin make-up usage (16/13%). The quality of life assessed by a self-administered French translation of the DLQI was moderately impaired and more in the ‘clinical acne’ group.Only 22% of women with ‘clinical acne’ were on medical therapy at the date of the survey versus 11% of women with ‘physiological acne’.This study confirms that acne in the adult female is more frequent than currently accepted. A high percentage starts during adulthood without any acne during adolescence. Scars are frequent. In all studies, few adult females had sought out medical treatment. The reasons varied: they were not bothered by their acne; they thought that their acne would clear spontaneously, or they believed that there was no effective therapy. In our study, among women in the acne group who received some form of medical treatment, one third were taking oral medication. Topical treatment is often irritating. Our study shows that women with acne had sensitive skin. The management of acne in the adult female is difficult. Oral therapies are not very effective and the acne is desperately recurring. Topical therapy is not well tolerated.Men seem to be less frequently concerned in all studies.

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