title: Prevalence of asthma in a large group of Israeli adolescents: influence of country of birth and age at migration.
abstract: BACKGROUND
  The occurrence of asthma has geographic variations and is lower in developing compared with industrialized countries. Both environmental and genetic factors may influence its prevalence. We aimed to evaluate the importance and effect of immigration (country of birth and age at immigration to Israel) on the prevalence of asthma in a large group of Israeli adolescents.
  
  
  METHODS
  Computerized medical records of 17-year-old adolescents, who underwent routine examination before military recruitment, were studied. The sample comprised both native-born Israelis (NBI) and immigrants from Ethiopia, the Former Soviet Union (FSU), and Western countries (WC). Asthma was defined as clinical symptoms and signs compatible with the disease accompanied by abnormal spirometry or documented chronic use of inhaled steroids.
  
  
  RESULTS
  Our cohort consisted of 1 466 654 adolescents, including 1 317 556 (89.8%) NBI and 149 098 (10.2%) immigrants. The prevalence of asthma at age 17 was higher in NBI compared with Ethiopian immigrants [4.7% (61 921) vs 2.6% (418), respectively, P < 0.0005], lower compared with immigrants from WC [5.6% (2177), P < 0.0005], and similar to immigrants from the FSU. Further analysis of the association between age at immigration and the risk for developing asthma showed that the younger immigrants from the FSU and Ethiopia arrived to Israel, the higher their prevalence of asthma at the age of 17 was.
  
  
  CONCLUSIONS
  Both environmental and genetic factors seem to influence the prevalence of asthma in 17-year-old adolescents. However, the higher risk for developing asthma associated with young age of immigration points toward an environmental predominance.
authors.affiliation: Department of Internal Medicine A, Meir Medical Center, Kfar Saba, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Pereg
authors.forename: A
authors.initials: A
authors.lastname: Tirosh
authors.forename: M
authors.initials: M
authors.lastname: Lishner
authors.forename: A
authors.initials: A
authors.lastname: Goldberg
authors.forename: T
authors.initials: T
authors.lastname: Shochat
authors.forename: R
authors.initials: R
authors.lastname: Confino-Cohen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001249:Asthma / Q000453:epidemiology* / Q000235:genetics; D004641:Emigration and Immigration; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007557:Israel; D008297:Male; D015995:Prevalence; D012307:Risk Factors