Descriptive epidemiology of acne vulgaris in the community.

Acne is a common skin condition. No universally accepted standardized classification system for acne vulgaris exists, although there is a strong need for it. Thus, the clinical definition of acne has been unclear in many studies. The reported prevalence of acne varies from 35 to over 90% of adolescents at some stage. In some studies the prevalence of comedones approaches 100% in both sexes during adolescence. The prevalence of acne varies between sexes and age groups, appearing earlier in females than in males, possibly reflecting the earlier onset of puberty. There is a greater severity of acne in males than in females in the late teens, which is compatible with androgens being a potent stimulus to sebum secretion. The prevalence of acne at a given age has been shown to be highly dependent on the degree of sexual maturity. Acne commonly shows a premenstrual increase in women. Some studies have detected seasonal variability in acne vulgaris, with the colder months associated with exacerbation and the warmer months showing improvement. Other studies have not confirmed these findings. Several studies that have investigated the psychosocial impact of acne have had conflicting results. The prevalence of severe acne has decreased over the past 20 years due to improved treatment. The general prevalence figure for acne may be confounded by treatment and this factor needs to be accounted for when collecting data.