A longitudinal study on the relationship between methacholine airway hyperresponsiveness and exercise-induced bronchoconstriction

Kim, Chang Seong; Choi, Inseon S; Kim, Sang Hoon; Woo, Hak; Sim, Hyeon Jeong; Han, Eui Ryoung

Abstract

BACKGROUND/AIMS
The airway hyperresponsiveness (AHR) in asthma has variable and persistent components that are related to airway inflammation and remodeling, respectively. This longitudinal study examined the relationship of airway responses between exercise (reflecting variable AHR) and methacholine (reflecting persistent AHR).
METHODS
The charts were reviewed of 36 young adult males who underwent both methacholine and exercise challenges at different times and were diagnosed with exercise-induced asthma. The severity of the response to each stimulus was scored (0~3).
RESULTS
The mean interval between the baseline and follow-up tests was 9.8 (5~58) months. The AHR score was significantly lower with the exercise challenge than with methacholine at follow-up (1.58+/-0.16 vs 1.19+/-0.15, p<0.01), but not at baseline. Compared to baseline, the AHR score was significantly lower with exercise (1.67+/-0.13 vs 1.19+/-0.15, p<0.01), but not with methacholine, and the difference in the AHR scores between exercise and methacholine increased significantly from baseline to follow-up (0.03+/-0.13 vs 0.39+/-0.13, p<0.05). The maximum fall in the forced expiratory volume in 1 s following exercise was significantly related to methacholine AHR (r=-0.571, p<0.001).
CONCLUSIONS
Exercise-induced bronchoconstriction was significantly related to methacholine AHR. However, the change in methacholine AHR in a follow-up test was significantly lower than that in the exercise response, which might have resulted from persistent worsening of the AHR with time because methacholine AHR reflects both variable and persistent AHR.