This Figure is based on definitions from the Global Initiative for Chronic Obstructive Lung Disease (GOLD).^[2]  Diagnosis and classification of COPD requires spirometry, which measures the forced vital capacity (FVC) and the forced expiratory volume in 1 second (FEV1).  An FEV1-to-FVC ratio of <0.7 indicates obstructive lung disease, and when a patient has a history of tobacco use or some other combustible exposure, as well as symptoms of shortness of breath, cough, or sputum production, then they would have a clinical diagnosis that is confirmed to be COPD.

The severity of COPD is also classified based on this spirometric value.  However awareness that numbers alone are not the only measure of a patient’s clinical profile has led to the GOLD guidelines.^[2]  These guidelines allow healthcare professionals to better match their patient’s profile to the guidelines’ patient profile and thereby allows them to optimize their therapy.