Chronic obstructive pulmonary disease: less common causes--an algorithm for the primary care physician.

The clinical features and distinguishing characteristics of the less common causes of chronic airflow obstruction have been reviewed. Clearly, the majority of patients have cigarette-induced chronic bronchitis and/or emphysema. However, for those patients with chronic airflow obstruction who are younger than 40 years old and/or have no or modest (less than 20 pack-years) smoking histories, a detailed assessment is warranted. A logical approach to the evaluation of the patient with dyspnea and chronic airflow obstruction has been outlined, with the goal of identifying those patients with potentially reversible disease, and to underscore the fact that not all "COPD" is due to cigarette smoking.