Objective: To determine the association between environmental tobacco smoke and middle ear disease in pre-school age children.
Design: A population-based case-control study with verification of disease history and exposure reporting in a subsample.
Setting and participants: Participants were identified through a population-base probability sample of 1320 first-grade students in 36 schools in Calgary, Alberta. The parents of 625 children meeting case (n = 227) or control (n = 398) definitions were interviewed by telephone for their children's exposure history. The adequacy of exposure and disease measures was assessed using hair continue measurements, home visits, and physician medical records for 92 children.
Main outcome measures and results: A history of middle ear disease was found in 23.9% of the sample. Relationships were found between middle ear disease and 2 or more household smokers (crude odds ratio) [OR], 1.85; 95% confidence interval [CI], 1.15-2.97), 10 or more cigarettes smoked by the mother per day (crude OR, 1.68; 95% CI, 1.12-2.52), and 10 or more cigarettes smoked in total in the household per day (crude OR, 1.40; 95% CI, 0.98-2.00) during the first 3 years of life. In logistic regression modeling these effects persisted after adjusting for child care (type, age started, duration, and group size), infant feeding (type and duration), socioeconomic status, maternal education level, number of prenatal ultrasonographic examinations, and health services use. The mean current hair cotinine levels were higher for children living in homes with 1 or more smokers vs no smokers (0.51 vs 0.31 ng/mg, P = .01). There was fair agreement (75.3%) between physician medical records and parental report of disease history, but some misclassification bias toward the null hypothesis likely.
Conclusion: Environmental tobacco smoke is an important risk factor for middle ear disease in urban preschool-age children, even in a relatively affluent population.