Predicting risk of airflow obstruction in primary care: Validation of the lung function questionnaire (LFQ)

Summary The Lung Function Questionnaire (LFQ) is being developed as a case finding tool to identify patients who are appropriate for spirometry testing to confirm the diagnosis of chronic obstructive pulmonary disease (COPD). The cross-sectional study reported herein was conducted to validate the LFQ, to identify item-response scales associated with the best accuracy, and to determine the impact on accuracy of the addition of another item on activity limitations (AL). Patients ≥ 40 years old seen at 2 primary care offices completed the LFQ, a demographic questionnaire followed by spirometry. Of the 837 evaluable patients, 18.6% had airflow obstruction (forced expiratory volume in 1 s/forced vital capacity [FEV 1 /FVC]  p 1 /FVC  1 /FVC  1