COPD is a chronic, progressive disease showing great variation in its natural history. Spirometry providing data on FEV 1 and FVC is the most common measure of disease progression. A large cohort of patients with COPD of GOLD stage II+ followed up every 6 months for 3 years showed a mean annual decline in FEV 1 of 33 mL. An annual decline in FEV 1 >40 mL was seen in 38% of the patients, while 8% showed an average annual increase of 20 mL. Current smoking and emphysema are related to more rapid decline in FEV 1 .
In addition to rapid decline in FEV 1 , factors that indicate a poor prognosis in established COPD are frequent exacerbations, respiratory insufficiency, nutritional status and comorbidities.
Smoking cessation is the most important intervention that affects the prognosis of the disease.