Persisting airflow limitation in asthmatics receiving routine self-adjusted medication.

Sixty-two patients with moderate asthma adjusted their routine medication (bronchodilator aerosol 59/62, beclomethasone dipropionate 55/62) to control their symptoms to their own and their doctor's satisfaction. They recorded peak expiratory flow (PEF) 3 times daily over about 8 months. PEF and spirometry were performed before and after aerosolised salbutamol on hospital attendances at monthly intervals. The subjects were classified as having Persistent Airflow Limitation (PAL) if every measurement, including that following a bronchodilator, persistently failed to reach a value of at least the predicted minus 2 SD. PAL was present in 7/62 by using FEV1 and in 27/62 using PEF. PAL was related to patient's age (p less than 0.02) and to duration of asthma (p less than 0.02). Flow-volume curves (available in 46/62 patients) correlated closely with PEF recorded at home on the same morning. Maximum expiratory flows at 50% and 25% of FVC were significantly lower in patients with PAL (assessed by PEF) than in those without PAL, suggesting more severe small airways dysfunction in those with PAL.