Validity of physician-diagnosed COPD in relation to spirometric definitions of COPD in a general population aged 50–64 years – the SCAPIS pilot study
Received 7 March 2017
Accepted for publication 19 June 2017
Published 4 August 2017 Volume 2017:12 Pages 2269—2275
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Kjell Torén,1,2 Nicola Murgia,1,2 Anna-Carin Olin,1 Jan Hedner,3 John Brandberg,4 Annika Rosengren,5 Göran Bergström5
1Section of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden; 2Section of Occupational Medicine, Respiratory Diseases and Toxicology, University of Perugia, Italy; 3Department of Medicine/Lung Medicine, Sahlgrenska Academy, University of Gothenburg, 4Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 5Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden
Background: In epidemiological studies, items about physician-diagnosed COPD are often used. There is a lack of validation and standardization of these items.
Materials and methods: In a general population-based study, 1,050 subjects completed a questionnaire and performed spirometry, including forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) after inhalation of 400 µg of salbutamol. COPD was defined as the ratio of FEV1/FVC <0.7 after bronchodilation. Physician-diagnosed COPD was defined as an affirmative answer to the single item: “Have you ever had COPD diagnosed by a physician?”, physician-diagnosed COPD/emphysema as an affirmative answer to any of the two single items; “Have you ever had COPD diagnosed by a physician?” or “Have you ever been told by a physician that you have emphysema?”, physician-diagnosed chronic bronchitis as an affirmative answer to; “Have you ever been told by a physician that you have chronic bronchitis?” and physician-diagnosed COPD, emphysema or chronic bronchitis was defined as an affirmative answer to either of the three items above.
Results: For the single item about physician-diagnosed COPD, the sensitivity was around 0.11 and the specificity was almost 0.99 in relation to COPD. The sensitivity of the combined items about COPD/emphysema in detecting COPD was 0.11 and the specificity was high, 0.985. When the items about physician-diagnosed COPD, emphysema or chronic bronchitis were merged as one entity, the sensitivity went up (0.13) and the specificity went down (0.95).
Conclusion: Items about physician-diagnosed COPD have low sensitivity but a very high specificity, indicating that these items will minimize the proportion of false positives. The low sensitivity will underestimate the total burden of COPD in the general population. Items about physician-diagnosed COPD may be used in studies of risk factors for COPD, but are not recommended in prevalence studies.
Keywords: validity, questionnaire, general-population, obstructive lung diseases, epidemiology
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