In 2001 the Global Initiative for Chronic Obstructive Lung Disease (GOLD) committee published its first consensus report [1]. At that time the authors suggested that the assessment of chronic obstructive pulmonary disease (COPD) should be primarily based on the extent of airflow limitation. In the following years, evidence accumulated that COPD is a complex and heterogeneous disease and that airflow limitation is not closely correlated to a variety of patient-related outcomes [2]. These findings, and the intent to create a more comprehensive system to better reflect the situation of an individual patient, were the basis for a novel concept recently published by GOLD. Now, the assessment is no longer based on the extent of airflow limitation alone; in addition, the patient's exacerbation history and symptoms are taken into account [3]. Based on the severity of symptoms and the exacerbation risk, four categories (A, B, C and D) were defined.
Since then, this novel assessment scheme has been studied in several existing cohorts, ranging from more than 2000 clinically stable COPD patients in the ECLIPSE study (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) [4], over a more broadly composed cohort of 4000 smokers from the COPDGene study [5], to population samples from Copenhagen [6] …
