Obstructive lung diseases: COPD, asthma, and many imitators

Chronic obstructive pulmonary disease (COPD) is a common respiratory disord er that occurs in 10% to 15% of people who smoke, an estimated 16 million A mericans. Asthma is also common. Spirometry is generally used to detect ear ly COPD in smokers and to evaluate patients with respiratory symptoms. Alth ough COPD and asthma account for most obstructive lung diseases, a broad sp ectrum of other disorders, including bronchiectasis, upper airway lesions, bronchiolar diseases, and some interstitial lung diseases, are associated w ith airflow obstruction. These less common forms of obstructive lung diseas es are often misdiagnosed because of their uncommon occurrence and poor rec ognition. We describe the heterogeneous spectrum of disorders that can pres ent with evidence of airflow obstruction and outline a diagnostic approach to obstructive lung disease.