Epidemiology of acne in the general population: the risk of smoking

BACKGROUND: Acne is a common skin disorder, but epidemiological data from the general population obtained by examination are scarce. Clinical experience suggests an association between smoking and acne, although confirmatory evidence from appropriate studies is lacking. OBJECTIVES: To determine the prevalence and demographic factors of acne in a general population sample and to investigate the association of smoking and acne on a qualitative and quantitative level. METHODS: In a cross-sectional study, 896 citizens (aged 1--87 years, median 42) of the City of Hamburg were dermatologically examined. The prevalence and severity of acne were recorded and further information on demographic variables, medical history, and alcohol and cigarette consumption were obtained by a standardized interview. RESULTS: According to the clinical examination, acne was present in 26.8% overall, and was more prevalent in men (29.9%) than women (23.7%) (odds ratio, OR 1.37, 95% confidence interval, CI 1.01--1.87). Prevalence followed a significant linear trend over age with peak prevalence between 14 and 29 years (P < 0.001). The reported age at onset was significantly lower in women than men (P = 0.015). According to multiple logistic regression analyses acne prevalence was significantly higher in active smokers (40.8%, OR 2.04, 95% CI 1.40--2.99) as compared with non-smokers (25.2%). A significant linear relationship between acne prevalence and number of cigarettes smoked daily was obtained (trend test: P < 0.0001). In addition, a significant dose-dependent relationship between acne severity and daily cigarette consumption was shown by linear regression analysis (P = 0.001). CONCLUSIONS: Smoking is a clinically important contributory factor to acne prevalence and severity.