title: Two distinct phenotypes of asthma in elite athletes identified by latent class analysis.
abstract: BACKGROUND
  Clusters of asthma in athletes have been insufficiently studied. Therefore, the present study aimed to characterize asthma phenotypes in elite athletes using latent class analysis (LCA) and to evaluate its association with the type of sport practiced.
  
  
  METHODS
  In the present cross-sectional study, an analysis of athletes' records was carried out in databases of the Portuguese National Anti-Doping Committee and the Norwegian School of Sport Sciences. Athletes with asthma, diagnosed according to criteria given by the International Olympic Committee, were included for LCA. Sports practiced were categorized into water, winter and other sports.
  
  
  RESULTS
  Of 324 files screened, 150 files belonged to asthmatic athletes (91 Portuguese; 59 Norwegian). LCA retrieved two clusters: "atopic asthma" defined by allergic sensitization, rhinitis and allergic co-morbidities and increased exhaled nitric oxide levels; and "sports asthma", defined by exercise-induced respiratory symptoms and airway hyperesponsiveness without allergic features. The risk of developing the phenotype "sports asthma" was significantly increased in athletes practicing water (OR = 2.87; 95% CI [1.82-4.51]) and winter (OR = 8.65; 95% CI [2.67-28.03]) sports, when compared with other athletes.
  
  
  CONCLUSIONS
  Two asthma phenotypes were identified in elite athletes: "atopic asthma" and "sports asthma". The type of sport practiced was associated with different phenotypes: water and winter sport athletes had three- and ninefold increased risk of "sports asthma". Recognizing different phenotypes is clinically relevant as it would lead to distinct targeted treatments.
authors.affiliation: a Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine , University of Porto, Portugal and Serviço de Imunoalergologia, Centro Hospitalar São João E.P.E. , Porto , Portugal .
authors.forename: Mariana
authors.initials: M
authors.lastname: Couto
authors.affiliation: b Norwegian School of Sport Sciences , Oslo , Norway .
authors.forename: Julie
authors.initials: J
authors.lastname: Stang
authors.affiliation: c Portuguese National Anti-Doping Organization , Lisbon , Portugal .
authors.forename: Luís
authors.initials: L
authors.lastname: Horta
authors.affiliation: b Norwegian School of Sport Sciences , Oslo , Norway .
authors.forename: Trine
authors.initials: T
authors.lastname: Stensrud
authors.affiliation: d Department of Clinical Epidemiology, Predictive Medicine and Public Health, Faculty of Medicine , University of Porto , Porto , Portugal .
authors.forename: Milton
authors.initials: M
authors.lastname: Severo
authors.affiliation: e Department of Pediatrics , Oslo University Hospital , Oslo , Norway , and.
authors.forename: Petter
authors.initials: P
authors.lastname: Mowinckel
authors.affiliation: a Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine , University of Porto, Portugal and Serviço de Imunoalergologia, Centro Hospitalar São João E.P.E. , Porto , Portugal .
authors.forename: Diana
authors.initials: D
authors.lastname: Silva
authors.affiliation: a Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine , University of Porto, Portugal and Serviço de Imunoalergologia, Centro Hospitalar São João E.P.E. , Porto , Portugal .
authors.forename: Luís
authors.initials: L
authors.lastname: Delgado
authors.affiliation: a Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine , University of Porto, Portugal and Serviço de Imunoalergologia, Centro Hospitalar São João E.P.E. , Porto , Portugal .
authors.forename: André
authors.initials: A
authors.lastname: Moreira
authors.affiliation: b Norwegian School of Sport Sciences , Oslo , Norway .|e Department of Pediatrics , Oslo University Hospital , Oslo , Norway , and.|f Institute of Clinical Medicine, University of Oslo , Oslo , Norway.
authors.forename: Kai-Håkon
authors.initials: KH
authors.lastname: Carlsen
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000145:classification* / Q000175:diagnosis / Q000453:epidemiology*; D001250:Asthma, Exercise-Induced / Q000453:epidemiology; D056352:Athletes; D001944:Breath Tests; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D006801:Humans; D009569:Nitric Oxide; D009664:Norway; D010641:Phenotype; D011174:Portugal; D065631:Rhinitis, Allergic / Q000453:epidemiology*; D012307:Risk Factors; D013177:Sports; D055815:Young Adult
chemical_list: D009569:Nitric Oxide
keywords: Asthma; athletes; clusters; exercise-induced bronchoconstriction; latent class analysis; phenotypes; sports; training environment