Clin Exp Dermatol. 2009 May 26; Law MP, Chuh AA, Lee A, Molinari NSummary Background. Data are lacking on the prevalence of acne, its effects on quality of life (QOL) and the treatment usage among Chinese patients in late adolescence. Aim. To derive data about the prevalence and predictive factors of acne, the disability caused by acne and choice of treatment used by Chinese late adolescents in Hong Kong. Methods. This was a cross-sectional study of a random sample of 389 entrants in a university in Hong Kong, using the Global Acne Grading System (GAGS) to measure the clinical severity of acne and the Cardiff Acne Disability Index (CADI) to measure QOL. Results. The response rate was 99.3%. The prevalence of acne was of 81.5% (95% CI 77.6-85.4%) and coexisted with a high frequency of acne disability at a rate of 81.8% (95% CI 78.1-85.6%). Assessment of the clinical severity of acne did not correlate strongly with the effect on QOL (gamma(s) = 0.445, P < 0.001). Over the previous 6 months, 30.3% of subjects had used topical treatments, 3.9% had taken systemic conventional western drugs and 3.2% of the subjects had used traditional Chinese medicine. Multivariate logistic regression was used to explore the predictive factors for acne disability. Female gender (P = 0.002), higher GAGS score (P < 0.001), higher perceived stress (P = 0.01) and willingness to pay Hong Kong$15 000 ( pound970) for a hypothetical permanent cure (P = 0.03) were positive predictors. Conclusions. Acne is prevalent in Hong Kong and has considerable psychological effects. The association between clinical severity and impaired QOL is not strong.