Chronic obstructive pulmonary disease: knowing what we mean, meaning what we say.

Chronic obstructive pulmonary disease (COPD) is defined in several different ways using different criteria based on symptoms, physiological impairment and pathological abnormalities. While some use COPD to mean smoking related chronic airway disease, others include all disorders causing chronic airway obstruction. When COPD is used as a broad descriptive term, specific disorders that cause chronic airway obstruction remain under-diagnosed and the prevalence estimates vary considerably. The lack of agreement over the precise terminology and classification of COPD has resulted in widespread confusion. Terminology includes definition, diagnostic criteria, and a system for staging severity. Recently, COPD is defined more clearly and diagnosed using precise criteria that include tobacco smoking greater than 10 pack years, symptoms and airway obstruction on spirometry. A multi-dimensional severity grading system, the BODE (body mass index, obstruction, dyspnoea, and exercise tolerance) index has been designed to assess the respiratory and systemic expressions of COPD. This review proposes that the broad group of chronic disorders of the airways (with or without airway obstruction) be called chronic airway disease (CAD). The term COPD should be used exclusively for tobacco smoking related chronic airway disease. Chronic airway obstruction or obstructive lung disease may be used to define those conditions with airways obstruction caused by factors other than tobacco smoking. The aetiology may be appended to the label, for example, chronic airway obstruction/obstructive lung disease associated with bronchiectasis, chronic airway obstruction/obstructive lung disease associated with obliterative bronchiolitis or chronic airway obstruction/obstructive lung disease due to biomass fuel/occupational exposure.