Early acute otitis media: determined by exposure to respiratory pathogens.

The purpose of the present study is to assess the relationship between early acute otitis media (AOM) and exposure to respiratory pathogens mediated by siblings and day-care. A prospective cohort of 3,754 Norwegian children born in 1992-93 was followed from birth through 12 months. One or more episodes of AOM had been experienced by 25% of the children before age one. Logistic regression analysis showed that siblings attending day-care is the most important risk factor for early AOM (ORadj = 1.9 (1.4-2.3)). The total number of children in the day-care setting is another determinant for early AOM (ORadj = 2.0 (1.4-2.6) in groups of 4 or more other children and ORadj = 1.3 (1.0-1.7) in groups of 1-3 other children as compared with those who are cared for alone). Siblings who attend day-care and the number of children in the child's own day-care setting are the most important determinants for AOM the first year of life.