Persistence of airway obstruction and hyperresponsiveness in subjects with asthma remission.

This study was designed to determine if there is residual airflow obstruction and/or airway hyperresponsiveness in adults with symptomatic asthma remission, and if age at remission or its duration influence these parameters. We studied 30 subjects, (20 men, 10 women, 28 atopics, aged 18 to 61 years; mean, 32 years) with a history of asthma (mean duration, 2 to 33 years) but who reported no symptoms or medication requirement for > or 2 years. They were individually matched for age, sex, and atopy, to a control group of 30 subjects without history of asthma. Each subject had a respiratory questionnaire and measurements of expiratory flows, lung volumes, and bronchodilator response. Morning/evening peak expiratory flow rates (PEFRs) were recorded for a 2-week period and two methacholine inhalation tests were obtained on separate days. Initial FEV1 and FVC for ex-asthmatics (controls) were, respectively, 91.0 +/- 2.5 percent and 97.8 +/- 2.3 percent (104.1 +/- 1.9 and 104.0 +/- 1.8 percent) of predicted values. Twenty nine ex-asthmatics (15 controls) had occasional respiratory symptoms, not attributed to asthma. Most subjects with asthma remission had evidences of mild airflow obstruction, associated to a methacholine response either increased in 11 (PC20 methacholine, 0.18 to 5.6 mg/ml) or "borderline" in 10 others (PC20 between 8 and 20 mg/ml). Airway responsiveness was normal (PC20 > 20 mg/ml) in 8 ex-asthmatics and in 21 controls (PC20 was under 8 mg/ml and between 10 and 20 mg/ml in, respectively, 5 and 4 controls). Mean reversibility of FEV1 after 200 micrograms of albuterol was 5.7 (range, -1.1 to 14.1 percent) compared with 2.5 (-4.4 to 10.5) in controls. Mean and maximal diurnal variation of PEFR were, respectively, 4.6 +/- 0.4 percent and 12.3 +/- 1.3 percent (controls, 2.9 +/- 0.3 and 7.0 +/- 0.8 percent). There was a significant correlation between PC20 and age at the diagnosis of asthma or at the onset of remission. Airway responsiveness was significantly less when asthma or remission of asthma occurred at a younger age, although there was no difference for baseline FEV1 and no significant correlation between PC20 and duration of asthma or of remission. Perception of bronchoconstriction was similar in both controls and ex-asthmatics. In conclusion, most ex-asthmatics who considered to be in asthma remission showed a persistent increase in airway responsiveness with or without mild airflow obstruction, suggesting that symptom report may be insufficient to determine that asthma is in true remission.