Asthma vs. non-specific reversible airflow obstruction: clinical features and responsiveness to anticholinergic drugs.

85 subjects with 20% reversibility in FEV1 were classified into the categories of asthma (55 patients) and non-specific airflow obstruction (30 patients), respectively, on the basis of the presence or absence of eosinophilia (in the blood or sputum). Asthmatics were further subdivided into the atopic and non-atopic subgroups, respectively, on the basis of skin prick tests. Clinically, paroxysmal nocturnal wheezing was more significantly associated with asthma than with non-specific airflow obstruction. Atopic asthmatics were distinguished from patients with non-specific airflow obstruction by their younger age at presentation and at onset of obstructive symptoms, by a history of allergic provocation of wheezing, a family history of asthma and other atopic diseases, and by a lower incidence of mucus hypersecretion. The last 3 symptoms also distinguished atopic from non-atopic asthma. Furthermore, unlike patients with non-atopic asthma or patients with non-specific airflow obstruction, atopic asthmatics had a significant impairment of bronchodilator responsiveness to inhaled anticholinergic drugs.