Reproducibility of eucapnic voluntary hyperpnoea for exercise-induced bronchoconstriction diagnosis in asthmatic children and adolescents.

Abstract

Respiratory symptoms after exercise are frequently reported by asthmatic patients, and exercise-induced bronchoconstriction (EIB) is a frequent cause, which requires objective testing for diagnosis. Eucapnic voluntary hyperpnea (EVH) is recommended as a surrogate stimulus for this purpose. Its short-term reproducibility is not yet established in children and young adolescents with asthma. To evaluate the short-term test-retest agreement and reproducibility of FEV1 changes after EVH in this population. Asthmatic patients aged between 10 and 20years underwent EVH for EIB diagnosis on two occasions 2-4days apart at a specialized university clinic. FEV1 was measured at 5, 15, and 30min after EVH with a target ventilation rate 21 times the baseline FEV1 . EIB was diagnosed as a decrease ≥10% in FEV1 from baseline. A total of 26 of 62 recruited individuals tested positive for EIB on both visits (positive group) and 17 on one visit only (divergent group), while 19 tested negative on both visits (negative group). The overall agreement was 72.5% (95%CI 61.6%, 83.6%), and Cohen's kappa coefficient was 0.452. Low bias (0.87%) and high intra-class correlation coefficient (0.854, 95%CI 0.758,0.912; p<.001) for FEV1 response between test days were found, but with wide limits of agreement (±20.72%). There were no differences in pre-challenge FEV1 or achieved ventilation rate between visits either between groups (p=.097 and p=.461) or within groups (p=.828 and p=.780). There were no safety issues. More than one EVH test should be performed in children and young adolescents with asthma to exclude EIB and minimize misdiagnosis and mistreatment.