title: Prevalence of asthma and associated factors in adolescents living in Belem (Amazon region), Para, Brazil.
abstract: BACKGROUND
  The prevalence of asthma in the Brazilian Amazon region is unknown. We studied the prevalence of asthma and associated factors in adolescents (13-14 years old) living in Belem, a large urban centre in this region.
  
  
  METHODS
  3725 adolescents were evaluated according to the International Study of Asthma and Allergies in Childhood (ISAAC) protocol and a random sample of them (126 asthmatics and 254 non-asthmatics) were assessed for possible risk factors by a supplementary questionnaire (ISAAC Phase II) and skin prick tests with aeroallergens. The association between asthma and associated factors was determined by logistic regression analysis.
  
  
  RESULTS
  3708 adolescents were enrolled, 48% were male. The prevalence of asthma in the last 12 months (identified as asthmatics) and the medical diagnosis of asthma were 20.7% and 29.3%, respectively. Risk factors significantly associated with asthma were: previous diagnosis of tuberculosis (odds ratio [OR]=38.9; 95% confidence interval [95% CI]: 4.6-328.0) and measles (OR=4.7; 95% CI: 2.3-9.8), breastfeeding for any length of time (OR=4.2; 95% CI: 1.1-15.2), current rhinitis (OR=3.2; 95% CI: 1.8-5.9), exposure to smokers (OR=2.4; 95% CI: 1.2-4.5), moisture in home (OR=1.8; 95% CI: 1.1-3.2) and rhinitis diagnosed by physician (OR=1.7; 95% CI: 1.2-2.9). Sensitisation to at least one aeroallergen was significantly higher among asthmatic adolescents (86.5% vs. 32.4%; p<0.0001).
  
  
  CONCLUSIONS
  The prevalence of asthma was similar to that observed in other Brazilian centres. Physician-diagnosed asthma was more frequent than the presence of symptoms suggestive of asthma. Infectious diseases, nutritional and environmental factors, as well as concomitant allergic rhinitis, were the main risk factors associated with the development of asthma in these adolescents.
authors.affiliation: Department of Integrated Healthy, Division of Pediatrics, Para State University, Para, Brazil. Electronic address: brunopaesbarreto@terra.com.br.
authors.forename: B A P
authors.initials: BA
authors.lastname: Barreto
authors.affiliation: Division of Allergy, Clinical Immunology and Rheumatology, Department of Pediatrics, Federal University of Sao Paulo - Escola Paulista de Medicina, Sao Paulo, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Sole
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology*; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012307:Risk Factors
keywords: Allergic rhinitis; Asthma; Children; Epidemiology; Risk factors; Tuberculosis