Supplementary Material for: Exposure to Environmental Tobacco Smoke and Prevalence of Atopic Dermatitis among Adolescents in Kuwait

Background: This study aimed to (i) assess the prevalence of exposure to environmental tobacco smoke (ETS) at homes, (ii) assess the prevalence of atopic dermatitis and (iii) evaluate the association between ETS exposure and atopic dermatitis status among adolescents. Methods: During October 2015, a cross-sectional study design was implemented using a self-administered, modified version of the ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire among students enrolled in nine high schools of one of the six governorates of Kuwait. Prevalence of ETS exposure at home (1 or more smokers at home vs. none) and atopic dermatitis were computed. A multivariable log-binomial regression model was used to evaluate the adjusted association between ETS exposure and atopic dermatitis. Results: Of 800 invited students, 746 (93.3%) participated, of whom 74.8% were Kuwaiti and 50.1% were female with a mean (SD) age of 16.8 (0.68) years. Prevalence of ETS exposure at home was 54%. Prevalence of atopic dermatitis was 14.9%. A final multivariable log-binomial regression model showed that compared with the adolescents free from atopic dermatitis, adolescents with atopic dermatitis were significantly more likely to have had ETS exposure at home (adjusted prevalence ratio = 1.49; 95% CI: 1.03–2.14; p = 0.034) or tended to be female (adjusted prevalence ratio = 1.42; 95% CI: 0.99–2.03; p = 0.054). Conclusions: A high prevalence of ETS exposure at home among adolescents was recorded. ETS exposure and female gender were significantly associated with atopic dermatitis status. Intervention fostering voluntary adoption of a smoke-free home rule may help protect the adolescents against ETS exposure and alleviate the menace of associated morbidity.