title: Overdiagnosis of asthma in obese and nonobese adults.
abstract: BACKGROUND
  It is unclear whether asthma is overdiagnosed in developed countries, particularly among obese individuals, who may be more likely than nonobese people to experience dyspnea.
  
  
  METHODS
  We conducted a longitudinal study involving nonobese (body mass index 20-25) and obese (body mass index >/= 30) individuals with asthma that had been diagnosed by a physician. Participants were recruited from 8 Canadian cities by means of random-digit dialing. A diagnosis of current asthma was excluded in those who did not have evidence of acute worsening of asthma symptoms, reversible airflow obstruction or bronchial hyperresponsiveness, despite being weaned off asthma medications. We stopped asthma medications in those in whom a diagnosis of asthma was excluded and assessed their clinical outcomes over 6 months.
  
  
  RESULTS
  Of 540 individuals with physician-diagnosed asthma who participated in the study, 496 (242 obese and 254 nonobese) could be conclusively assessed for a diagnosis of asthma. Asthma was ultimately excluded in 31.8% (95% confidence interval [CI] 26.3%-37.9%) in the obese group and in 28.7% (95% CI 23.5%-34.6%) in the nonobese group. Overdiagnosis of asthma was no more likely to occur among obese individuals than among nonobese individuals (p = 0.46). Of those in whom asthma was excluded, 65.5% did not need to take asthma medication or seek health care services because of asthma symptoms during a 6-month follow-up period.
  
  
  CONCLUSIONS
  About one-third of obese and nonobese individuals with physician-diagnosed asthma did not have asthma when objectively assessed. This finding suggests that, in developed countries such as Canada, asthma is overdiagnosed.
authors.affiliation: Ottawa Health Research Institute, Ottawa, Ont, USA. saaron@ohri.ca
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Aaron
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Vandemheen
authors.forename: Louis-Philippe
authors.initials: LP
authors.lastname: Boulet
authors.forename: R Andrew
authors.initials: RA
authors.lastname: McIvor
authors.forename: J Mark
authors.initials: JM
authors.lastname: Fitzgerald
authors.forename: Paul
authors.initials: P
authors.lastname: Hernandez
authors.forename: Catherine
authors.initials: C
authors.lastname: Lemiere
authors.forename: Sat
authors.initials: S
authors.lastname: Sharma
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Field
authors.forename: Gonzalo G
authors.initials: GG
authors.lastname: Alvarez
authors.forename: Robert E
authors.initials: RE
authors.lastname: Dales
authors.forename: Steve
authors.initials: S
authors.lastname: Doucette
authors.forename: Dean
authors.initials: D
authors.lastname: Fergusson
mesh_terms: D000328:Adult; D017677:Age Distribution; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology*; D015992:Body Mass Index; D001835:Body Weight; D002170:Canada / Q000453:epidemiology; D016001:Confidence Intervals; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D005260:Female; D005541:Forced Expiratory Volume; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D016017:Odds Ratio; D015995:Prevalence; D011336:Probability; D012016:Reference Values; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D017678:Sex Distribution; D013147:Spirometry