Association between smoking habits and acne. A case-control study and a systematic review and meta-analysis

Background: Smoke increases the development of many diseases. Previous studies about its role in the pathogenesis of acne show contradictory results. The objective of this paper is to conduct a case control study on the relationship between smoke and acne and a systematic review of case-control studies on this association. Methods: For the case-control study, a questionnaire was administrated to each participant, to assess the association acne-tobacco smoking. For the systematic review, a bibliographic search on electronic databases was performed (Pubmed, Scopus and Google Scholar). Only case-control studies in English-language from 1966 to 2010 were included. All publications were analyzed by two researchers. Quality assessment was performed using a score for observational study. Results: Of 93 cases of the case-control study, 6 patients had severe acne, 19 moderate acne and 68 had a mild acne, according to classification of Global Alliance to improve outcomes in acne. No one of the smokers had severe acne, only one smoker had moderate acne and 11 had mild acne. Smoking was associated with acne (crude OR = 7.26; 95%CI: 2.27-23.18; Adjusted OR = 5.47; 95%CI: 1.67-17.97). The systematic review considered five population studies. First meta-analysis, with all investigations, showed a OR=2.03 (95% CI: 0.63-6.58). The sensitivity analyses include meta-analyses stratified by gender, and quality (score>6). Results for males were: OR=1.89 (95%CI:1.25-2.87); for female OR=1.84 (95%CI:0.36-9.51). The analysis using quality score reported OR=3.48, (95%CI: 1.58-7.68). Conclusi onS: In conclusions, smokers have higher risk to develop acne, especially males. Conclusions are not robust, because of heterogeneity definitions of smokers and acne grading.