Prevalence of exercise-induced bronchial lability in families of children with asthma

Abstract

Exercise tests and skin tests were performed in 65 members of the families of 12 children with asthma. A positive response to skin and exercise challenge frequently, but not invariably, occurred together. Abnormal exercise-induced bronchial lability was found in 33% of relatives with a past history of asthma, in 40% of those with hay fever, and in 32% of the clinically healthy relatives. The subjects with active asthma chiefly had a tendency to bronchoconstriction, while the other labile subjects chiefly had a tendency to bronchodilatation. The total proportion of all subjects affected by clinically evident atopic diseases, positive skin tests, or increased bronchial lability was 85%. The importance of using a challenge test to detect a hidden tendency for asthma in family studies is discussed.