The Global Initiative for Chronic Obstructive Lung Disease (GOLD) advocates the use of multidimensional prognostic indices for staging, monitoring and guiding decision-making in chronic obstructive pulmonary disease (COPD) [1]. The previous severity staging based on airflow limitation has been substituted for a grading (ABCD) system that also includes exacerbations and symptoms [1]. On the other hand, comorbidities are frequent in COPD, and patients often die from other diseases than COPD. De Torres et al.
