title: Overdiagnosis of asthma in the community.
abstract: BACKGROUND
  Overdiagnosis of asthma may be an emerging problem after years of attention to the rising prevalence and reported underdiagnosis of the disease.
  
  
  OBJECTIVE
  A sample of adult asthmatics from the community was investigated to determine whether they met the current diagnostic criteria for asthma.
  
  
  METHODS
  Ninety participants were studied from a self-referred sample of physician-labelled, adult asthmatics from the community. The setting was a tertiary care, university-affiliated teaching hospital in Halifax, Nova Scotia. Three diagnostic criteria from the Canadian Thoracic Society Asthma Guidelines were used to demonstrate the presence of asthma: first, positive symptom history, and either, second, reversible airflow obstruction demonstrable on spirometry or documented peak expiratory flow rate diurnal variability, or, third, bronchial hyperreactivity to methacholine.
  
  
  RESULTS
  At the time of the study, 41% of a sample of physician-labelled asthmatics showed no evidence of reversible airflow obstruction and had a negative methacholine challenge. By backward logistical regression analysis, a higher mean number of medications used (P<0.01), a lower forced expiratory volume in 1 s (P<0.05) and using inhaled steroids (P<0.05) were predictive of meeting the diagnostic criteria for asthma. Sixty-two per cent of subjects who did not meet the criteria for asthma were currently taking medications for "asthma". Only 52.2% of the subjects reported ever having undergone pulmonary function testing.
  
  
  CONCLUSIONS
  Overdiagnosis of asthma is a potential problem, which may result in unnecessary or inappropriate medication use, increased health care costs and mislabelling of patients. The authors recommend greater use of objective diagnostic tests such as spirometry, peak flow diaries and bronchial provocation to establish a clinical diagnosis of asthma.
authors.affiliation: Dalhousie University, Halifax, Canada.
authors.forename: Jorin
authors.initials: J
authors.lastname: LindenSmith
authors.forename: Debra
authors.initials: D
authors.lastname: Morrison
authors.forename: Carole
authors.initials: C
authors.lastname: Deveau
authors.forename: Paul
authors.initials: P
authors.lastname: Hernandez
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology; D003153:Community Health Services; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D009674:Nova Scotia / Q000453:epidemiology; D015995:Prevalence; D012129:Respiratory Function Tests; D013147:Spirometry
chemical_list: D000305:Adrenal Cortex Hormones; D016210:Methacholine Chloride