Epidemiology of Acne

Abstract

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 r