Chapter 43 - Diagnosis

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Asthma and chronic obstructive pulmonary disease (COPD) are different inflammatory disorders that share a common functional feature: airflow limitation. Airflow limitation in asthma is generally reversible, either spontaneously or with treatment. However, in COPD it is poorly reversible and usually progressive. When considering the typical clinical and functional features of these two diseases, the differential diagnosis between asthma and COPD is relatively simple. In this context, asthma is usually recognized in a young, atopic, nonsmoking subject with recurrent dyspnea, wheezing or chest tightness, and variable reversible airflow limitation. COPD, on the other hand, is commonly diagnosed in patients older than 40, with a history of cigarette smoking and with dyspnea, chronic cough, sputum, and fixed airflow limitation. However, distinguishing asthma from COPD involves the clinical presentation of the patient and particularly his or her history. Pulmonary function tests, and particularly spirometry, exhibit an almost complete reversibility of airflow limitation in asthma and poorly reversible airflow limitation in COPD, thereby allowing the confirmation of the diagnosis. In borderline elderly patients, differential diagnosis becomes difficult because several characteristics overlap and the patient develops poor reversible airflow limitation and responds partially to treatment. The differential diagnosis mainly aims at providing better treatment, and it becomes important to undertake an individual approach so as to maximize the benefits.