The Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2011 recommendations stratified patients with chronic obstructive pulmonary disease (COPD) into four severity groups (A–D) [1]. However, the clinical trials on which these recommendations were based did not use this patient classification. Within group D, patients may be stratified into subgroups according to the criteria that determine their inclusion: either forced expiratory volume in 1 s (FEV1), frequency of exacerbations or both [2–4]. These D-subgroups display significantly different treatment outcomes [2]. The current report determined whether budesonide/formoterol prevented exacerbations more effectively than formoterol alone in symptomatic patients with COPD at high and low risk of exacerbations acc...