New insights into the pathophysiology of mild chronic obstructive pulmonary disease.

The classification of mild chronic obstructive pulmonary disease (COPD) requires a postbronchodilator forced expiratory volume in 1 s (FEV1) to forced vital capacity ratio <0.7 and an FEV1 ≥80% predicted. Given their relatively well-preserved spirometry, some have argued that respiratory symptoms in patients with mild COPD are unlikely to be related to pulmonary function abnormalities and that early detection of COPD is a 'waste of resources'. Despite this viewpoint, there is emerging clinical and physiological evidence of peripheral airway dysfunction, diminished quality of life and reduced physical activity levels, and increased mortality, hospitalizations, dyspnea and exercise intolerance in patients with mild COPD compared with healthy controls. The purpose of the present focused review was to summarize recent research regarding the pathophysiology and treatment of mild COPD.