Diagnosing exercise-induced bronchoconstriction with eucapnic voluntary hyperpnea: is one test enough?

BACKGROUND In athletic individuals, a secure diagnosis of exercise-induced bronchoconstriction (EIB) is dependent on objective testing. Indirect bronchoprovocation testing is often used in this context and eucapnic voluntary hyperpnea (EVH) testing is recommended for this purpose, yet the short-term reproducibility of EVH is yet to be appropriately established. OBJECTIVE The aim of this study was to evaluate the reproducibility of EVH in a cohort of recreational athletes. METHODS A cohort of recreational athletes (n = 32) attended the laboratory on two occasions to complete an EVH challenge, separated by a period of 14 or 21 days. Spirometry and impulse oscillometry was performed before and after EVH. Training load was maintained between visits. RESULTS Prechallenge lung function was similar at both visits (P > .05). No significant difference was observed in maximum change in FEV1 (ΔFEV1max) after EVH between visits (P > .05), and test-retest ΔFEV1max was correlated (intraclass correlation coefficient = 0.81; r(2) = 0.66; P = .001). Poor diagnostic reliability was observed between tests; 11 athletes were diagnosed with EIB (on the basis of ΔFEV1max ≥10%) at visit 1 and at visit 2. However, only 7 athletes were positive at both visits. Although there was a small mean difference in ΔFEV1max between tests (-0.6%), there were wide limits of agreement (-10.7% to 9.5%). Likewise, similar results were observed for impulse oscillometry between visits. CONCLUSIONS In a cohort of recreational athletes, EVH demonstrated poor clinical reproducibility for the diagnosis of EIB. These findings highlight a need for caution when confirming or refuting EIB on the basis of a single indirect bronchoprovocation challenge. When encountering patients with mild or borderline EIB, we recommend that more than one EVH test is performed to exclude or confirm a diagnosis.