[Asthmatic characteristics in smokers with advanced emphysema]

Most pneumologists assume that chronic asthma and emphysema associated with smoking differ both in their etiology and type of inflammation. However, it is difficult to study subjects who have both diseases simultaneously. We designed a prospective study to determine whether or not some advanced emphysema patients who are smokers have an asthmatic profile suggesting the two diseases overlap.

Twenty-three smokers with moderate to severe obstruction and radiologic signs of advanced emphysema were studied. The following signs of asthma were analyzed for all patients: positive acute response to bronchodilators, eosinophilia in peripheral blood, significant eosinophilia in sputum, significant total serum immunoglobulin E (IgE) and specific IgE positive for common allergens and fungi. An asthmatic profile was defined as the presence of 3 or more of the aforementioned signs. Statistical analysis was by calculation of the confidence interval on the total number of positive cases to estimate the population percentage.

Data on at least 4 characteristics were available for 21 of the 23 patients. Ten (48%) of the 21 had asthmatic profiles (3 or more of the aforementioned characteristics). This finding suggests that asthmatic characteristics are present in between 17.6 and 79.6% of the studied population with advanced emphysema, with a confidence interval of 99.9%.

We conclude that emphysema initially associated with smoking may mean that at least 17.6% of patients have a clear asthmatic profile, which indicates a high degree of overlap between asthma and emphysema in smokers. Thus, our findings are consistent with the Dutch theory that chronic obstructive diseases have a common origin in underlying allergic sensitization and bronchial hyperresponsiveness alongside various other influential factors such as tobacco smoking over the course of disease.