Development of the Lung Function Questionnaire (LFQ) to identify airflow obstruction
Barbara P Yawn1, Douglas W Mapel2, David M Mannino3, Fernando J Martinez4, James F Donohue5, Nicola A Hanania6, Mark Kosinski7, Regina Rendas-Baum7, Matthew Mintz8, Steven Samuels9, Anand A Dalal10, On behalf of the Lung Function Questionnaire Working Group*
1Olmsted Medical Center, Department of Research, Rochester, MN, USA; 2Lovelace Clinic Foundation, Albuquerque, NM, USA; 3University of Kentucky School of Medicine, Lexington, KT, USA; 4University of Michigan Health System, Ann Arbor, MI, USA; 5University of North Carolina School of Medicine, Chapel Hill, NC, USA; 6Baylor College of Medicine, Houston, TX, USA; 7QualityMetric, Inc., Lincoln, RI, USA; 8George Washington University School of Medicine, Washington, DC, USA; 9Indiana Internal Medicine Consultants, Greenwood, IN, USA; 10GlaxosmithKline, Research Triangle Park, NC, USA; *The Lung Function Questionnaire Working Group includes Barbara P Yawn, Douglas W Mapel, David M Mannino, Fernando Martinez, James Donohue, Nicola Hanania, Matthew Mintz, and Steven Samuels
Objective: To describe the item-selection and item-reduction for the Lung Function Questionnaire (LFQ), being developed to help clinicians identify patients appropriate for diagnostic evaluation for chronic obstructive pulmonary disease (COPD) using spirometry.
Methods: Item selection and reduction were based on information from 387 ≥40-year-old respondents to the third National Health and Nutrition Examination Survey who had self-reported chronic bronchitis. Item reduction involved stepwise logistic regression. The accuracy of the final subset of items for identifying individuals with airflow obstruction (forced expiratory volume in one second/forced vital capacity <0.70) versus those without it was assessed with receiver operating characteristic analysis. Content and face validity were assessed using focus groups of primary care physicians (n = 16) and interviews with COPD patients (n = 16).
Results: The model with all five items (age; smoking history; the presence of wheeze, dyspnea, and phlegm) compared with models with combinations of fewer items had the highest classification accuracy (area under the curve [AUC] = 0.720) with sensitivity and specificity of 73.2% and 58.2%, respectively. The presence of three or more factors yielded the highest AUC, a result suggesting that three or more affirmative answers is the most appropriate criterion indicating presence of airflow obstruction.
Conclusions: The five-item LFQ retained sufficient accuracy, sensitivity, and specificity in identifying individuals with COPD for further validation testing.
Keywords: spirometry, chronic obstructive pulmonary disease, respiratory disease, chronic bronchitis, diagnosis, screening
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