Bronchial hypersensitivity in asthmatics in long-term symptom-free state

Effect of inhaled budesonide on bronchial hyperresponsiveness in adolescents with clinical remission of asthma

STUDY OBJECTIVE

Many children with asthma go into long-term clinical remission at adolescence, but bronchial hyperresponsiveness (BHR) persists in some of these subjects. The regular use of inhaled corticosteroids improves BHR in patients with symptomatic asthma. The aim of this study was to determine whether BHR in adolescents with asthma remission could be reduced by prolonged treatment with inhaled corticosteroids.

DESIGN

A randomized, double-blind, placebo-controlled, parallel study.

PATIENTS

Thirty-seven adolescents with BHR and long-term remission of their asthma (neither symptoms nor any medication use during the previous 2 years).

INTERVENTION

Subjects received inhaled budesonide (two 200-microg puffs bid; budesonide group, n = 19) or identical placebo (placebo group, n = 18) for 9 months. A separate group of patients with symptomatic asthma (symptomatic group, n = 19), using the same regimen of budesonide, was also studied.

MEASUREMENTS AND RESULTS

The provocative concentration of methacholine producing a 20% fall in FEV(1) (PC(20)) was measured before and every 3 months during treatment. There was no significant difference among the three groups for the baseline PC(20). In neither the placebo nor the budesonide group did the geometric mean of PC(20) change significantly over the 9-month period. In contrast, a significant increase in PC(20) was noted in the symptomatic group as a result of the budesonide treatment.

CONCLUSION

Our data have shown that budesonide inhaled regularly for 9 months did not cause a significant improvement in the BHR of adolescents with long-term asthma remission. This suggests that the mechanism underlying BHR in this clinical setting may be different from that in symptomatic asthma.

Bronchial sensitivity to histamine in former asthmatics: redevelopment of symptoms during a year of followup

The aim of this protocol was to study bronchial responsiveness in 23 former asthmatics who were free of symptoms for at least 5 years. Bronchial hyperreactivity (BHR) was evaluated with histamine challenge test and the results were compared with those of 20 normal subjects and 20 current asthmatic patients. Among the former asthmatics 65% fulfilled the criteria of BHR. During 1 year of followup, two former asthmatics redeveloped asthma symptoms. Interestingly, one patient had no BHR when initially tested. These findings suggest that the absence of BHR does not guarantee the nonrecurrence of asthma symptoms in former asthmatics.

The spectrum of irritant-induced asthma: sudden and not-so-sudden onset and the role of allergy

A retrospective investigation of 86 asthmatic subjects defined clinical features of irritant-induced asthma and assessed the contributory role of an allergic predisposition. Three categories of asthma were evaluated: (1) occupational asthma due to a sensitizer (11 subjects, 13%); (2) irritant-induced asthma (54 persons, 63%); and (3) not occupational/environmental exposure-related asthma (21 subjects, 24%). Two distinct clinical presentations of irritant-induced asthma emerged: the first was sudden onset (29 subjects) and the second was not so sudden in onset (25 subjects). Sudden-onset, irritant-induced asthma was analogous to the reactive airways dysfunction syndrome. Clinical manifestations began immediately or within a few hours (always within 24 h) following an accidental, brief, and massive exposure. In contrast, for the not-so-sudden-onset asthma subjects, the causative irritant exposure was not brief, usually not massive, continued for > 24 h, and the initiation of asthma took longer to evolve. Eighty-eight percent of individuals with not-so-sudden irritant-induced asthma displayed an atopy/allergy status (p < 0.01). Some of the atopy/allergy subjects with presumed new-onset asthma were found to have suffered preexisting asthma that had been clinically quiescent for at least 1 year before the triggering exposure (16 persons). We conclude that preexisting allergic/atopy and/or preexisting asthma were significant contributors to the pathogenesis of not-so-sudden, irritant-induced asthma and emphasizes a critical interaction between environmental and host factors in the pathogenesis of asthma.

Residual abnormalities of pulmonary function in asymptomatic young adult asthmatics with childhood-onset asthma

We investigated the pulmonary function of male asthmatics with childhood-onset asthma. Our results revealed that adult asthmatics with mild symptoms apparently have abnormal pulmonary function. On the other hand, after a 3-6-month symptom-free period, and even after inhalation of bronchodilator, they still showed significant residual abnormalities in pulmonary function. Pulmonary function tests are very sensitive tools for the assessment of airway limitations during an acute asthmatic attack. However, these tests are not sensitive enough to detect residual abnormalities in asymptomatic asthmatics. Although the positive predictive rate for detecting small airway dysfunction in asymptomatic asthmatics is not high, FEF25-75 proved to be the best (63.2%) among the conventional pulmonary function parameters. We therefore suggest using FEF25-75 instead of FEV1 or peak flow rate in clinical practice for the conventional assessment of effectiveness of treatment, especially in the follow-up of asthmatic patients. More sensitive and simple tests are required in the future for detection of small airway dysfunction in asymptomatic asthmatics. Moreover, strict and early treatment of this abnormality with steroids is mandatory to prevent the formation of sequelae.

Clinical features of adult-relapse asthma in comparison with those of child-onset asthma and adult-onset asthma

Clinical features of adult-relapse asthma (group B, n = 15) were compared with those of child-onset asthma (group A, n = 18) and adult-onset asthma (group C, n = 34) in terms of allergic component and bronchial hypersensitivity. The percentage of patients with high levels of serum IgE (> 300 U/ml) in groups A, B, and C was 83%, 73%, and 50%, respectively, and the percentage of patients with positive IgE RAST for house dust was 87.5%, 78.6%, and 46.7%, and that for mite was 93.3%, 92.9%, and 58.6% in groups A, B, and C, respectively. The histamine concentration of PC20 for the bronchial hypersensitivity test in groups A, B, and C was 196 micrograms/ml, 500 micrograms/ml, and 724 micrograms/ml, respectively. Thus, the adult-relapse asthma was closer to the child-onset asthma type in allergic state and closer to the adult-onset asthma type in bronchial hypersensitivity state. The classification employed here seemed to provide some merits in delineating the features of adulthood asthma.