Characteristics of bronchial asthma with incomplete reversibility of airflow obstruction.
BACKGROUND
Incomplete reversibility of airflow obstruction (IRAO) can be observed in some asthmatic patients without significant smoking history nor evidence of other respiratory condition. The characteristics of this group remain however to be defined.


METHODS
We compared 18 asthmatic patients with persistent airflow obstruction, defined as an FEV1 < or = 75% predicted despite optimal corticosteroid treatment, to others with complete reversibility of airflow obstruction, paired for age and gender (CRAO, FEV1 > 80% of predicted).


RESULTS
Mean duration of asthma was 31.6 years for IRAO patients and 17.7 for the CRAO group and mean baseline FEV1 was 48.6 +/- 2.6% and 89.3 +/- 3.4%, respectively. Patients with IRAO had more severe airflow obstruction and hyperinflation than those with CRAO, while lung compliance and CO diffusion were similar. Overall healthcare use was similar in the two groups, but those with IRAO had a greater global asthma-related 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 high resolution chest tomography compared with CRAO. Baseline FEV1 however, was not correlated with the measured airway wall thickness.


CONCLUSIONS
We found that asthmatic patients with IRAO have a more severe asthma and asthma of longer duration than asthmatic subjects with CRAO. 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.
Hudon
C
C
Unité de Recherche, Centre de Pneumologie de l'Hôpital Laval, Université Laval, Québec, Canada.
Turcotte
H
H
Laviolette
M
M
Carrier
G
G
Boulet
L P
LP
D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use; D000328:Adult; D000402:Airway Obstruction / Q000503:physiopathology*; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D001995:Bronchography; D002940:Circadian Rhythm; D004632:Emergency Medical Services; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006760:Hospitalization; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D012129:Respiratory Function Tests; D012882:Skin Tests; D011795:Surveys and Questionnaires; D014056:Tomography, X-Ray
D000305:Adrenal Cortex Hormones; D008688:Methacholine Compounds