RISK-FACTORS FOR CHILDHOOD ASTHMA AND WHEEZING - IMPORTANCE OF MATERNAL AND HOUSEHOLD SMOKING

To identify modifiable risk factors for wheezing illness in childhood, the associations between current asthma or wheezing and factors such as household smoking, damp and dietary salt preference were measured i n a questionnaire-based prevalence study of schoolchildren 7 to 9 yr o f age in Cape Town. In a random sample of 15 schools, questionnaires w ere completed by parents of 1,955 children, from which 368 cases and 2 94 controls were selected on the basis of reported asthma diagnosis or symptoms. Urinary cotinine concentrations were measured, and the pare nts were interviewed. An exposure-response relationship between the ur inary cotinine creatinine ratio and asthma/wheeze was observed. In mul tivariate analysis, predictors of asthma/wheeze were hay fever (odds r atio [OR] = 5.30; 95% confidence interval [CI] = 3.16 to 8.89), eczema (OR = 2.19; 95% CI = 1.33-3.62), parental asthma (OR = 1.77; 95% CI = 1.11 to 2.84), absence of paternal contribution to income (OR = 1.72; 95% CI = 1.17 to 2.54), maternal smoking in pregnancy (OR = 1.87; 95% CI = 1.25 to 2.81), and each additional household smoker (OR = 1.15; 95% CI = 1.01 to 1.30). Findings were similar, with higher odds ratios for most variables, except number of household smokers, when the grou p was restricted to children with parent-reported asthma. The findings confirm that household smoking is an important modifiable risk factor in asthma/wheeze among young schoolchildren, and they suggest that ma ternal smoking in pregnancy and current household exposure are indepen dent contributors to this effect.