Quality of life, stage severity and COPD.

F or a long time now, arbitrary boundaries have been used in the severity grading of chronic airflow limitation and chronic obstructive pulmonary disease (COPD). The lack of validation of these severity cut-points has been widely criticised, predominantly because they are based on clinical impressions and simplistic metrics. This is acknowledged by the Global Initiative of Chronic Obstructive Lung Disease (GOLD) guidelines, which state that ‘‘There is only an imperfect relationship between the degree of airflow limitation and the presence of symptoms. Spirometric staging, therefore, is a pragmatic approach aimed at practical implementation and should only be regarded as an educational tool and a general indication to the initial management’’ [1]. Evidence that the GOLD cut-points are inappropriate, however, has not been forthcoming despite the strongly held views that the divisions for airflow limitation into a convenient gradation from mild to very severe may only relate very loosely to the degree of functional impairment and the prognosis of COPD [2, 3].