Exposure to household secondhand tobacco smoke and the odds of developing atopic dermatitis among adolescents: A causal mediation analysis

Abstract

INTRODUCTION Exposure to household secondhand tobacco smoke (SHS) among adolescents has been shown to be associated with atopic dermatitis, and affects disproportionality females. However, the mechanisms underlying this link are uncertain. This study sought to identify modifiable factors that mediate the relationship between household SHS exposure and atopic dermatitis among adolescents. METHODS During October 2015, a cross-sectional study was conducted using the ISAAC questionnaire for data collection from adolescents enrolled in nine high schools of Hawalli – one of the six governorates of Kuwait. Data were collected on sociodemographic characteristics, self-reported tobacco smoking among adolescents, household SHS exposure (≥1 smokers at home vs none), self-reported asthma and atopic dermatitis. For causal mediation analysis an inverse odds-weighting approach was used. RESULTS Of 746 participants, 74.8% were Kuwaiti, 50.1% were female, 12.4% were regular daily smokers and 54.1% had household SHS exposure, which was more common among Kuwaiti (79.6%) than non-Kuwaiti (20.4%) adolescents. The prevalences of self-reported asthma and atopic dermatitis were 20.6% and 14.9%, respectively. After adjusting for the pre-exposure covariates (i.e. sex and nativity), household SHS exposure had a significant (p=0.043) total effect, non-significant (p=0.133) natural direct effect, and marginally insignificant (p=0.058) natural indirect effect, which were jointly mediated by asthma status and adolescent’s self-reported smoking status, with a proportion of mediated risk to atopic dermatitis of 29.6%. CONCLUSIONS Asthma and self-tobacco smoking among adolescents not only directly affected but also mediated household SHS exposure effect on atopic dermatitis risk. Voluntarily adopting a smoke-free home rule may minimize household SHS exposure, reduce the odds of developing asthma, and deter the initiation of tobacco smoking among adolescents. Such an effort will likely mitigate the atopic dermatitis risk among adolescents in this and other similar settings. If implemented, future studies may contemplate evaluating the impact of such intervention.