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