title: Regional variation in asthma symptom prevalence in Latin American children.
abstract: OBJECTIVE
  This study investigates the distribution pattern of asthma symptom prevalence in Latin American children aged 13-14 years.
  
  
  METHODS
  A randomized, cross-sectional and multicentric study on the prevalence and severity of asthma symptoms (lifetime asthma, current wheezing, and frequent sleep disturbance by wheezing) was conducted in 165,917 schoolchildren from 56 centers in 17 Latin American countries, as part of the International Study of Asthma and Allergies in Childhood (ISAAC), Phase Three.
  
  
  RESULTS
  The prevalence of lifetime asthma prevalence ranged from 1.2% to 33.1%, whereas current wheezing went from 3.9% to 30.8% and frequent sleep disturbance from 0.6% to 6.1%. An important proportion of centers (55%) reported a prevalence of asthma symptoms over 15%. There was no significant correlation between asthma symptom prevalence and latitude, altitude, or tropical setting. At country level, the prevalence of asthma was not associated with gross national income (GNI), proportion of population under the poverty line, or ancestry.
  
  
  CONCLUSIONS
  This study suggests that ecological interactions, probably typical for each locality, may be the main determinants for the large variability of asthma prevalence in Latin America. The high prevalence of asthma symptoms found in children living in areas with low socioeconomic development would challenge the protective role against asthma of factors related to low hygiene and poverty; contrarily, in this region they would act as risk factors.
authors.affiliation: Department of Pediatric Respiratory Medicine, Hospital CRS El Pino, University of Santiago de Chile (USACH), Santiago, Chile. jmallol@vtr.net
authors.forename: Javier
authors.initials: J
authors.lastname: Mallol
authors.forename: Dirceu
authors.initials: D
authors.lastname: Solé
authors.forename: Manuel
authors.initials: M
authors.lastname: Baeza-Bacab
authors.forename: Viviana
authors.initials: V
authors.lastname: Aguirre-Camposano
authors.forename: Manuel
authors.initials: M
authors.lastname: Soto-Quiros
authors.forename: Carlos
authors.initials: C
authors.lastname: Baena-Cagnani
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D017753:Ecosystem; D006801:Humans; D007843:Latin America / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012959:Socioeconomic Factors; D018709:Statistics, Nonparametric