Non-specific bronchial airway hyperreactivity and the diagnosis of asthma

In very mild and atypical cases of asthma, highly discriminative tests are needed to make the diagnosis. To demonstrate this, measurement of non-specific bronchial airway hyperreactivity by means of standardized bronchial inhalation challenge tests with histamine and methacholine were performed in 10 very mild asthmatic and nine normal control subjects; both groups included Nigerians who were temporarily resident in London at the time of the study. Bronchial reactivity was expressed as the provocative concentration of the agents causing a 20% fall in forced expiratory volume in 1 sec (PC20FEV1); higher values indicating lower levels of non-specific bronchial reactivity. The level of non-specific bronchial reactivity in these very mild asthmatics, whose baseline physiological data were not different from those in normals, was found to be 18-29 times higher than the normal control subjects. These tests very effectively discriminated between asthmatic and normal control subjects. With available resources it should be possible to study a large number of Nigerians in their own environment.