Changes in indices of airway hyperresponsiveness during one year of treatment with inhaled corticosteroids in patients with asthma.
We analyzed the changes in indices of airway hyperresponsiveness, including hypersensitivity and hyperreactivity, during one year of treatment with inhaled corticosteroids. We then investigated on which of them the inhaled corticosteroids had a primary effect. Fifty outpatients with asthma were recruited and treated with inhaled beclomethasone dipropionate. They underwent bronchoprovocation tests on the initial visit and at 3, 6, and 12 months. The dose of methacholine required to produce a 20% fall in the forced expiratory volume in 1 second (PD20-FEV1) was measured to evaluate airway hypersensitivity. A relatively novel index, the percent change in the forced vital capacity (deltaFVC%) at the PD20-FEV1, was assessed as a marker of airway hyperreactivity. PD20-FEV1 and deltaFVC% were assumed to indicate the horizontal shift of the dose-response curve and the vertical change in the maximal response plateau, respectively. Log(PD20-FEV1) and deltaFVC% continued to improve throughout the year (p < 0.001 and p = 0.002, respectively). Log(PD20-FEV1) improved significantly at the 3-month evaluation (p < 0.001), and deltaFVC% improved at the 6-month evaluation (p = 0.012). Log(PD20-FEV1) had no or weak relationships with deltaFVC% at all evaluation points. In conclusion, inhaled corticosteroids continued not only to reverse the leftward shift of the curve, but also to restore the plateau. Furthermore, their effect was reflected primarily by the former rather than the latter: They should be followed separately to examine how much airway inflammation is reduced.
Oga
T
T
Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Japan. ogat@kuhp.kyoto-u.ac.jp
Nishimura
K
K
Tsukino
M
M
Hajiro
T
T
Ikeda
A
A
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D000368:Aged; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage*; D001249:Asthma / Q000188:drug therapy*; D001507:Beclomethasone / Q000008:administration & dosage*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis*; D005260:Female; D005541:Forced Expiratory Volume; D005938:Glucocorticoids / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D016896:Treatment Outcome; D014797:Vital Capacity
D018927:Anti-Asthmatic Agents; D005938:Glucocorticoids; D001507:Beclomethasone