Classification of asthma based on clinical symptoms: asthma type in relation to patient age and age at onset of disease.

Seventy-one cases of bronchial asthma were classified into three types: bronchospasm, bronchospasm-hypersecretion and bronchiolar obstruction types. The characteristics of each type were studied in relation to patient age and age at onset of the disease. In the 71 subjects studied, the most frequent type was the bronchospasm type followed by the bronchospasm-hypersecretion type and bronchiolar obstruction type. Intractable asthma was most frequently observed in the bronchiolar obstruction type and least in the bronchospasm type. Most of the patients under 50 years of age showed the bronchospasm type. The bronchospasm-hypersecretion type was characteristically accompanied by blood eosinophilia when the patient age was under 50 years. In the bronchospasm-hypersecretion type, the incidence of intractable asthma was high in patients under 50 years of age, but not remarkable in those over 50. A large proportion of the patients over 50 years of age were of the bronchiolar obstruction type. There was no difference in the incidence of intractable asthma between the two groups classified by age at onset.