title: Prevalence of airway obstruction assessed by lung function questionnaire.
abstract: OBJECTIVE
  To estimate the prevalence of unidentified chronic obstructive pulmonary disease (COPD) and determine the screening accuracy of the Lung Function Questionnaire (LFQ).
  
  
  METHODS
  Cigarette smokers who had a smoking history of 10 or more pack-years and were aged 30 years or older were recruited from 36 centers from February 18, 2009, to May 29, 2009. A total of 1575 patients completed a Web-based survey including the 5-item LFQ. Spirometry was performed on patients with an LFQ total score of 18 or less and on a subset scoring more than 18. The primary outcome was the proportion of patients at risk of airflow obstruction as measured by the LFQ (score, ≤ 18) in whom an airflow obstruction was confirmed by spirometry.
  
  
  RESULTS
  Of the patients who completed the LFQ, 849 (54%) had standardized spirometry data available. On the basis of LFQ and spirometry results, the estimated prevalence of possible COPD was 17.9% (95% confidence interval, 15.3%-20.6%). At a cut point of 18 or less, sensitivity, specificity, positive predictive value, and negative predictive value of the LFQ were 88%, 25%, 21%, and 90%, respectively. Approximately 1 in 5 patients (21%) aged 30 years or older and 1 in 4 (26%) aged 50 years or older scored 18 or less on the LFQ and had a ratio of forced expiratory volume in the first second of expiration to forced vital capacity less than 0.70.
  
  
  CONCLUSIONS
  On the basis of postbronchodilator spirometry results using weighted estimates, approximately 1 in 5 patients (21%) aged 30 years or older with a smoking history of 10 or more pack-years seen in a primary care setting is likely to have COPD. The LFQ could be a helpful COPD case-finding tool for clinicians to identify patients who need further evaluation.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT01013948.
authors.affiliation: Department of Medicine, George Washington University School of Medicine, Washington, DC, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Mintz
authors.forename: Barbara P
authors.initials: BP
authors.lastname: Yawn
authors.forename: David M
authors.initials: DM
authors.lastname: Mannino
authors.forename: James F
authors.initials: JF
authors.lastname: Donohue
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Hanania
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Grellet
authors.forename: Alicia W
authors.initials: AW
authors.lastname: Gilsenan
authors.forename: Lori D
authors.initials: LD
authors.lastname: McLeod
authors.forename: Anand A
authors.initials: AA
authors.lastname: Dalal
authors.forename: Ibrahim H
authors.initials: IH
authors.lastname: Raphiou
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Prillaman
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Crater
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Cicale
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Mapel
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D011320:Primary Health Care; D011594:Psychometrics; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*; D013147:Spirometry; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology