Eucapnic voluntary hyperpnoea for the diagnosis of exercise-induced bronchoconstriction: is one test enough?

Background: Exercise-induced bronchoconstriction (EIB) is highly prevalent in endurance athletes and may impact on their health and performance. In athletes a secure diagnosis is dependent upon objective testing and the eucapnic voluntary hyperpnoea (EVH) test is recommended for this purpose. The short and long-term repeatability of EVH in the setting of amateur athletes is not established, yet has implications for both screening and treatment surveillance. Methods: Thirty-six sub-elite athletes were recruited to take part in the present study. Subjects were required to attend the laboratory on three separate occasions separated by a short-term period of either 14 or 21 days and a long-term period of 10 months respectively. Pulmonary function assessment including spirometry and impulse oscillometry (IOS) was conducted before and following an EVH challenge. Results: Over the short-term period eleven athletes were diagnosed with EIB at visit one and eleven athletes at visit two. Only seven athletes were positive at both visits. Over the long-term period nine athletes were diagnosed with EIB at visit one and ten athletes at visit two. No significant difference was observed in maximum change in FEV1 (∆FEV1max) post EVH between visits (P = 0.115) and test-retest ∆FEV1max was strongly correlated (ICC = 0.76; r2 = 0.58; P = 0.001). Although there was only a small bias in ∆FEV1max between tests (-1.56%) the data exhibited wide limits of agreement (-13.8 – 10.7%). Conclusion: In our cohort of sub-elite athletes, EVH demonstrated poor repeatability over both short and long-term periods. These findings highlight the need for caution when considering confirming or refuting a diagnosis of EIB based on a one-time indirect bronchoprovocation test utilising a cut-off value of 10% fall in FEV1.