Environmental tobacco smoke and the risk of eczema symptoms among school children in South Africa: a cross-sectional study

Objective: The aim of this study was to investigate the association between eczema ever (EE) and current eczema symptoms (ES) in relation to exposure to environmental tobacco smoke (ETS). Design: A cross-sectional study using the International Study of Asthma and Allergies in Childhood questionnaire. Setting: 16 schools were randomly selected from two neighbourhoods situated in Ekurhuleni Metropolitan Municipality, Gauteng Province, South Africa. Participants: From a total population of 3764 school children aged 12-14 years, 3468 completed the questionnaire (92% response rate). A total of 3424 questionnaires were included in the final data analysis. Primary outcome: The prevalence of EE and current ES was the primary outcome in this study. Results: Data were analysed using Multilevel Logistic Regression Analysis (MLRA). The likelihood of EE was increased by exposure to ETS at home (OR 1.30 95% CI 1.01 to 1.67) and at school (OR 1.26 95% CI 1.00 to 1.60). The likelihood of EE was lower for males (OR 0.66 95% CI 0.51 to 0.84). The likelihood of ES was increased by ETS at home (OR 1.93 95% CI 1.43 to 2.59) and school (1.44 95% CI 1.09 to 1.90). The likelihood of ES was again lower for males (OR 0.56 95% CI 0.42 to 0.76). Smoking by mother/female guardian increased the likelihood of EE and ES, however, this was not significant in the multivariate analysis. Conclusions: Symptoms of eczema were positively associated with exposure to ETS at home and school. The results support the hypothesis that ETS is an important factor in understanding the occurrence of eczema.