CHARACTERISTICS OF BRONCHIAL-ASTHMA WITH INCOMPLETE REVERSIBILITY OF AIR-FLOW OBSTRUCTION

Background: Incomplete reversibility of airflow obstruction (IRAO) can be observed in some asthmatic patients without significant smoking hi story nor evidence of other respiratory condition. The characteristics of this group remain however to be defined. Methods: We compared 18 a sthmatic patients with persistent airflow obstruction, defined as an F EV(1) less than or equal to 75% predicted despite optimal corticostero id treatment, to others with complete reversibility of airflow obstruc tion, paired for age and gender (CRAO, FEV(1) > 80% of predicted). Res ults: Mean duration of asthma was 31.6 years for IRAO patients and 17. 7 for the CRAO group and mean baseline FEV(1) was 48.6 +/- 2.6% and 89 .3 +/- 3.4%, respectively. Patients with IRAO had more severe airflow obstruction and hyper inflation than those with CRAO, while lung compl iance and CO diffusion were similar. Overall healthcare use was simila r in the two groups, but those with IRAO had a greater global asthma-r elated discomfort, increased diurnal variation of airflow obstruction and used higher doses of inhaled corticosteroids than those with CRAO. Patients with IRAO had slightly increased airway wall thickness on hi gh resolution chest tomography compared with CRAO. Baseline FEV(1), ho wever, was not correlated with the measured airway wall thickness. Con clusion: We found that asthmatic patients with IRAO have a more severe asthma and asthma of longer duration than asthmatic subjects with CRA O. Our data suggest that in asthma, IRAO may result from long-standing airway inflammation and associated structural changes, although this remains to be further documented.