title: Prevalence and underdiagnosis of chronic obstructive pulmonary disease among patients at risk in primary care.
abstract: BACKGROUND
  People with known risk factors for chronic obstructive pulmonary disease (COPD) are important targets for screening and early intervention. We sought to measure the prevalence of COPD among such individuals visiting a primary care practitioner for any reason. We also evaluated the accuracy of prior diagnosis or nondiagnosis of COPD and identified associated clinical characteristics.
  
  
  METHODS
  We recruited patients from three primary care sites who were 40 years or older and had a smoking history of at least 20 pack-years. Participants were asked about respiratory symptoms and underwent postbronchodilator spirometry. COPD was defined as a ratio of forced expiratory volume in the first second of expiration to forced vital capacity (FEV(1)/FVC) of less than 0.7 and an FEV(1) of less than 80% predicted.
  
  
  RESULTS
  Of the 1459 patients who met the study criteria, 1003 (68.7%) completed spirometry testing. Of these, 208 were found to have COPD, for a prevalence of 20.7% (95% confidence interval 18.3%-23.4%). Of the 205 participants with COPD who completed the interview about respiratory symptoms before spirometry, only 67 (32.7%) were aware of their diagnosis before the study. Compared with patients in whom COPD had been correctly diagnosed before the study, those in whom COPD had been over-diagnosed or undiagnosed were similar in terms of age, sex, current smoking status and number of visits to a primary care practitioner because of a respiratory problem.
  
  
  CONCLUSIONS
  Among adult patients visiting a primary care practitioner, as many as one in five with known risk factors met spirometric criteria for COPD. Underdiagnosis of COPD was frequent, which suggests a need for greater screening of at-risk individuals. Knowledge of the prevalence of COPD will help plan strategies for disease management.
authors.affiliation: West Park Healthcare Centre, Toronto, Ont.
authors.forename: Kylie
authors.initials: K
authors.lastname: Hill
authors.forename: Roger S
authors.initials: RS
authors.lastname: Goldstein
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Guyatt
authors.forename: Maria
authors.initials: M
authors.lastname: Blouin
authors.forename: Wan C
authors.initials: WC
authors.lastname: Tan
authors.forename: Lori L
authors.initials: LL
authors.lastname: Davis
authors.forename: Diane M
authors.initials: DM
authors.lastname: Heels-Ansdell
authors.forename: Marko
authors.initials: M
authors.lastname: Erak
authors.forename: Pauline J
authors.initials: PJ
authors.lastname: Bragaglia
authors.forename: Itamar E
authors.initials: IE
authors.lastname: Tamari
authors.forename: Richard
authors.initials: R
authors.lastname: Hodder
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Stanbrook
mesh_terms: D000367:Age Factors; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D011320:Primary Health Care; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D013147:Spirometry