title: Prevalence of undiagnosed airflow obstruction among people with a history of smoking in a primary care setting.
abstract: OBJECTIVE
  The purpose of this study was to define the prevalence of undiagnosed airflow obstruction (AO) among subjects with a history of smoking but no previous diagnosis of chronic lung disease. The finding of AO likely represents diagnosis of chronic obstructive pulmonary disease.
  
  
  METHODS
  People aged ≥30 years with a history of smoking who attended public outpatient clinics for primary care services were included in this study.
  
  
  METHODS
  A cross-sectional survey in five clinics in Hong Kong using the Breathlessness, Cough, and Sputum Scale, the Lung Function Questionnaire, and office spirometry was conducted.
  
  
  RESULTS
  In total, 731 subjects (response rate =97.9%) completed the questionnaires and spirometry tests. Most of the subjects were men (92.5%) in the older age group (mean age =62.2 years; standard deviation =11.7). Of the 731 subjects, 107 had AO, giving a prevalence of 14.6% (95% confidence interval =12.1-17.2); 45 subjects with AO underwent a postbronchodilator test. By classifying the severity of chronic obstructive pulmonary disease using the Global Initiative for Chronic Obstructive Lung Disease, 27 (60%) were considered to be in mild category and 18 (40%) in moderate category. None of them belonged to the severe or very severe category. The total score of Lung Function Questionnaire showed that majority of the subjects with AO also had chronic cough, wheezing attack, or breathlessness, although most did not show any acute respiratory symptoms in accordance with the Breathlessness, Cough, and Sputum Scale. Diagnosis of AO was positively associated with the number of years of smoking (odds ratio =1.044,P=0.035) and being normal or underweight (odds ratio =1.605,P=0.046). It was negatively associated with a history of hypertension (odds ratio =0.491,P=0.003).
  
  
  CONCLUSIONS
  One-seventh of smokers have undiagnosed AO. Spirometry screening of smokers should be considered in order to diagnose AO at an early stage, with an emphasis on smoking cessation.
authors.affiliation: Department of Family Medicine and Primary Health Care, Kowloon West Cluster, Hospital Authority.
authors.forename: Sau Nga
authors.initials: SN
authors.lastname: Fu
authors.affiliation: Department of Medicine and Geriatrics, Princess Margaret Hospital.
authors.forename: Wai Cho
authors.initials: WC
authors.lastname: Yu
authors.affiliation: Department of Family Medicine and Primary Care, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR.
authors.forename: Carlos King-Ho
authors.initials: CK
authors.lastname: Wong
authors.affiliation: Department of Family Medicine and Primary Health Care, Kowloon West Cluster, Hospital Authority.
authors.forename: Margaret Choi-Hing
authors.initials: MC
authors.lastname: Lam
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control; D016009:Chi-Square Distribution; D003371:Cough / Q000453:epidemiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000453:epidemiology / Q000503:physiopathology; D042241:Early Diagnosis; D005260:Female; D006306:Health Surveys; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D015995:Prevalence; D011320:Primary Health Care; D065840:Protective Factors; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control; D012307:Risk Factors; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*; D016540:Smoking Cessation; D000074606:Smoking Prevention; D013147:Spirometry; D011795:Surveys and Questionnaires
keywords: COPD; airflow obstruction; chronic obstructive pulmonary disease; early diagnosis; general practice; smokers