The Global Initiative for Chronic Obstructive Lung Disease (GOLD) ABCD scheme for classifying patients with COPD with separate appraisal of air-flow limitation and symptoms and/or exacerbation risk. mMRC = modified Medical Research Council score; CAT = COPD Assessment Test. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) ABCD scheme for classifying patients with COPD with separate appraisal of air-flow limitation and symptoms and/or exacerbation risk. mMRC = modified Medical Research Council score; CAT = COPD Assessment Test. From Reference 1, with permission. Robert M Burkes, and James F Donohue Respir Care 2018;63:749-758 (c) 2012 by Daedalus Enterprises, Inc.