title: Swimming attendance during childhood and development of asthma: Meta-analysis.
abstract: BACKGROUND
  The association between asthma and swimming pool attendance has not been demonstrated and currently there are conflicting results. In order to clarify the association between asthma diagnosis in children and swimming pool attendance, and to assess the consistency of the available epidemiological studies, we completed a literature analysis on the relationship between the exposure to disinfection by-products in indoor swimming pools during childhood and asthma diagnosis.
  
  
  METHODS
  Following the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria, a systematic review and meta-analysis was performed by searching MEDLINE via PubMed, TOXNET, and Scopus databases (from inception to 20 April 2015) using the key word "Asthma" together with "swimming pool", "disinfection by-products", "indoor air pollution" and "children". Inclusion criteria were: English language, a complete analytic study design involving a cohort of children (0-16 years), a well-defined definition of exposure, and the presence of data on effect and variance. Studies on in vivo, in vitro or professional and accidental exposure were excluded.
  
  
  RESULTS
  After a screening process, seven reports (n = 5851 subjects) were included out of a total of 2928 references. The reported OR of the association between swimming pool attendance and asthma prevalence ranged from 0.58 to 2.30. The present meta-analysis failed to identify a significant difference in asthma development between children attending swimming pools and controls (OR, 1.084; 95% CI: 0.89-1.31).
  
  
  CONCLUSIONS
  Swimming in childhood does not increase the likelihood of doctor-diagnosed asthma. Based on this meta-analysis review, the association of the disease with indoor pool attendance is still unclear.
authors.affiliation: Public Health Unit, University of Rome "Foro Italico", Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Valeriani
authors.affiliation: Department of Public Health and Infectious Diseases, Sapienza University, Rome, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Protano
authors.affiliation: Department of Public Health and Infectious Diseases, Sapienza University, Rome, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Vitali
authors.affiliation: Public Health Unit, University of Rome "Foro Italico", Rome, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Romano Spica
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005060:Europe / Q000453:epidemiology; D006801:Humans; D007223:Infant; D016017:Odds Ratio; D015995:Prevalence; D012307:Risk Factors; D013550:Swimming; D013551:Swimming Pools
keywords: asthma; meta-analysis; swimming pool; swimming-associated illness; systematic review