Prevalence of recurrent wheezing in infants

Objective: To identify the prevalence of recurrent wheezing in infants in the city of Curitiba, PR, Brazil. Methods: A cross-sectional study carried out by means of administering questionnaires to the parents of infants aged 12 to 15 months attending health centers for immunization during the period between August 2005 and December 2006. This is a standardized and validated instrument consisting of questions on demographic characteristics, wheezing, respiratory infections and risk factors. At the time of the study the City Health Department had 107 health centers, 35 of which were selected by lots and distributed homogeneously across the municipal territory. Results: A total of 1,364 infants (45.4%) had episodes of wheezing during their first 12 months of life, with onset at 5.5+/-3.1 months (mean +/- standard deviation), and 678 (22.6%) had had three or more episodes. In 84.6% of the wheezing children treatment was with beta(2)-agonists, with inhaled corticosteroids in 18.5%, oral corticosteroids in 24.3% and leukotriene receptor antagonists were used with 5.4%. The wheezing children exhibited nocturnal symptoms, intense difficulty breathing and visits to emergency services in the proportions of 58.9, 46.2 and 57.6%, respectively; 12.7% were admitted to hospital for asthma and 10.9% had had a medical diagnosis of asthma. Nocturnal symptoms, visits to emergency, severity of symptoms, hospital admissions for asthma and medical diagnoses of asthma were all more common among those who had suffered three or more crises (p < 0.001). Conclusions: There is an elevated prevalence of wheezing among the infants of Curitiba, with early onset and elevated morbidity. It is possible that these infants represent a large contingent of asthmatics.