title: Population based study of risk factors for underdiagnosis of asthma in adolescence: Odense schoolchild study.
abstract: OBJECTIVE
  To describe factors related to underdiagnosis of asthma in adolescence.
  
  
  METHODS
  Subgroup analysis in a population based cohort study.
  
  
  METHODS
  Odense municipality, Denmark.
  
  
  METHODS
  495 schoolchildren aged 12 to 15 years were selected from a cohort of 1369 children investigated 3 years earlier. Selection was done by randomisation (n = 292) and by a history indicating allergy or asthma-like symptoms in subject or family (n = 203).
  
  
  METHODS
  Undiagnosed asthma defined as coexistence of asthma-like symptoms and one or more obstructive airway abnormalities (low ratio of forced expiratory volume in 1 second to forced vital capacity, hyperresponsiveness to methacholine or exercise, or peak flow hypervariability) in the absence of physician diagnosed asthma. Risk factors (odds ratios) for underdiagnosis.
  
  
  RESULTS
  Undiagnosed asthma comprised about one third of all asthma identified. Underdiagnosis was independently associated with low physical activity, high body mass, serious family problems, passive smoking, and the absence of rhinitis. Girls were overrepresented among undiagnosed patients with asthma (69%) and underrepresented among diagnosed patients (33%). Among the risk factors identified, low physical activity and problems in the family were independently associated with female sex. The major symptom among those undiagnosed was cough (58%), whereas wheezing (35%) or breathing trouble (50%) was reported less frequently than among those diagnosed. Less than one third of those undiagnosed had reported their symptoms to a doctor.
  
  
  CONCLUSIONS
  Asthma, as defined by combined symptoms and test criteria, was seriously underdiagnosed among adolescents. Underdiagnosis was most prevalent among girls and was associated with a low tendency to report symptoms and with several independent risk factors that may help identification of previously undiagnosed asthmatic patients.
authors.affiliation: Department of Medicine C, Odense University Hospital, Denmark. hc.siersted@winsloew.ou.dk
authors.forename: H C
authors.initials: HC
authors.lastname: Siersted
authors.forename: J
authors.initials: J
authors.lastname: Boldsen
authors.forename: H S
authors.initials: HS
authors.lastname: Hansen
authors.forename: G
authors.initials: G
authors.lastname: Mostgaard
authors.forename: N
authors.initials: N
authors.lastname: Hyldebrandt
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012129:Respiratory Function Tests; D012135:Respiratory Sounds / Q000175:diagnosis; D012307:Risk Factors; D017678:Sex Distribution; D014028:Tobacco Smoke Pollution
chemical_list: D014028:Tobacco Smoke Pollution