[Bronchial hyperreactivity and obstructive respiratory tract diseases. A 2.8 year follow-up study]

Nonspecific bronchial hyperreactivity (BHR) is under discussion as a possible risk factor for the development of chronic obstructive pulmonary disease.

Within the framework of a prospective study, we investigated the course of the disease in 50 inpatients with BHR, and the clinical symptoms of airways disease (coughing, dyspnea and expectoration) with no manifest airways obstruction at rest (Rt < 3.5 cm H2O/l/s) on admission to the hospital. The unspecific inhalative provocation challenge was carried out with metacholine. The presence of BHR was assumed when the resting respiratory resistance (Rt) of < 3.5 cm H2O/l/s increased to more than 6 cm H2O/l/s. On admission to hospital, all the patients were treated with inhalative bronchodilators and glucocorticosteroids.

After an average period of 2.8 years, BHR was no longer measurable in only 7 of the patients (14%), while 28 patients (56%) continued to have a BHR with clinical symptomatology presenting. In 15 patients (30%), manifest airways obstruction at rest, with an average Rt of 6.4 cm H2O/l/s developed. In patients with an uncharacteristic cough, dyspnea and unremarkable lung function parameters at rest, a provocation test should be done to identify BHR. A prognosis can, however, not be established on the basis of a single demonstration of BHR, but only after observation over a longer period.