Fig. 1

Classification of COPD patients to one of four groups, based on the ABCD classification tool (N = 3520), which takes into consideration the overall score in the CAT as well as the patients’ history of exacerbations, mild or leading to hospitalization, over the last 12 months. AE: annual exacerbations, ASE: annual severe (i.e. leading to the emergency department) exacerbations, AEL: annual exacerbation likelihood, ASEL: annual severe (i.e. leading to the emergency department) exacerbation likelihood, CAT: COPD assessment test, COPD: chronic obstructive pulmonary disease, CrH: COPD-related hospitalizations