296 Impact of inhaler therapy on hyperpnoea-induced bronchoconstriction in elite swimmers, and test-retest repeatability of EVH challenge in those non-adherent to therapy

Background Approximately 70% of elite swimmers experience exercise-induced-bronchoconstriction (EIB), with the eucapnic-voluntary-hyperpnoea (EVH) challenge recommended to provide objective evidence to support diagnosis. Research on the impact of inhaler therapy in elite swimmers with a positive EVH challenge (EIBpositive) is limited, and the repeatability of the EVH challenge questioned. Objective Investigate impact of inhaler therapy on hyperpnoea-induced-bronchoconstriction in EIBpositive elite swimmers adherent to therapy. Evaluate long-term test-retest repeatability of EVH challenge in those non-adherent to inhaler therapy. Design Retrospective data analysis. Setting Great Britain swimming team. Participants Nineteen elite-international swimmers (8 males, 11 females; 20±3 yrs). Interventions Following initial assessment, EIBpositive athletes were prescribed appropriate inhaler therapy in accordance to greatest fall in FEV1 (FEV1max) and asked to maintain therapy throughout the year. Athletes were grouped dependent on adherence to inhaler therapy (Non-adherent = EVH1→EVH2;n=13; adherent = EVHOFF→EVHON;n=6). Main outcome measurements Differences in FEV1max between screening visits separated by a calendar year were analysed using paired t-tests and presented as mean ± SD. The test-retest repeatability between EVH1→EVH2 was expressed as mean bias with 95% limits of agreement and Pearson’s correlation coefficient (rp). Results FEV1max was significantly lower in EVHON (-9.17±-3.4%) than EVHOFF (-26.7±-13.3%; p=0.02) and a trend for baseline FEV1 to be greater in EVHON than EVHOFF (p=0.06). EVH1→EVH2 FEV1max did not differ significantly between screening visits (p≥0.05). There was acceptable repeatability of FEV1max in EVH1→EVH2 (0.85%; -5.97, 7.67), and significant strong positive correlation (rp=0.72, p=0.01). Conclusions Elite swimmers adherent to inhaler therapy demonstrated significant reduction in FEV1max severity. The EVH challenge result was repeatable in elite swimmers with EIB non-adherent to inhaler therapy. Therefore, the EVH challenge is effective to initially assess elite swimmers for EIB, and use as a follow-up assessment after initiation of inhaler therapy.