Otitis media incidence and risk factors in a population-based birth cohort.

Otitis media is the main reason young children receive antibiotics and is the leading reason for physician visits. OBJECTIVE: To characterize the incidence, recurrence and risk factors for otitis media in a population-based birth cohort. METHODS: All children born in southwestern British Columbia during 1999 to 2000 were followed until the age of three years. Otitis media was defined using The International Classification of Diseases, Ninth Revision coding of physician visits, and linked with antibiotic prescription data. Information on sex, birth weight, gestational age, Aboriginal status, maternal age, older siblings, maternal smoking during pregnancy, breastfeeding initiation, neighbourhood income, female education and rural residence were obtained from vital statistics, birth hospitalizations, perinatal registry and census data.RESULTS: Complete risk factor information was available for 50,474 children (86% of all births). Nearly one-half of the children (48.6%) had one or more physician visits for otitis media during follow-up, and 3952 children (7.8%) met the definition for recurrent otitis media. Of the children with at least three visits during follow-up (n=7571), 73% had their initial visit during the first year of life. Aboriginal status, maternal age younger than 20 years, male sex and older siblings were the strongest risk factors identified in the adjusted conditional logistic regression models. DISCUSSION: The present study established a population-based birth cohort by linking multiple administrative databases to characterize the incidence of and risk factors for otitis media. Although the incidence of otitis media is generally low in southwestern British Columbia, important risk factors continue to be young maternal age, mothers who smoke during pregnancy and children with Aboriginal ancestry