We have evaluated risk factors associated with persistence of wheezing beyond the first two years of life among children living in a subtropical area.

80 children who had been seen at the Emergency Room for an episode of wheezing in the first 2 years of life were followed for 2 years in this prospective study. Children underwent clinical evaluation and skin prick testing to inhalant and food allergens two years following the index episode of wheezing. Detection of respiratory viruses and analysis of house dust samples for exposure to major allergens from mites, cockroach, cat and dog (by ELISA) were carried out at enrollment. Total IgE and specific IgE antibodies (Pharmacia CAP system) were measured at the beginning of the study and at the end of follow-up. Multivariate analysis was performed to identify factors associated with persistent wheezing.

73 children (44 boys) completed the study. After 2 years, 38 (52%) presented 3 or more wheezing episodes treated with beta-2 agonists in the past 12 months (persistent wheezers). Risk factors for persistence of wheezing were: family history of allergy (OR=48.6; p=0.03), exposure to levels of cockroach allergen Bla g 1 >2U/g in the kitchen (OR=7.6; p=0.03) and allergic sensitization at age 2-4 (OR=11.3; p=0.002). Breast-feeding for at least one month was a protective factor (OR=0.08; p=0.01).

Environmental exposure to high levels of cockroach allergen in infancy, sensitization to indoor allergens at age 2-4 and family history of allergy were strongly and independently associated with persistent wheezing in children.