Purpose: This study sought to determine and compare the levels of airway dysfunction and inflammation in a large cohort of symptomatic international athletes from pool- and non-pool-based sporting backgrounds. In total, 118 athletes were recruited.
Methods: All subjects had symptoms of exercise asthma and were steroid naïve. They completed baseline spirometry, a symptom score, exhaled nitric oxide, a eucapnic voluntary hyperventilation (EVH) test, and a postchallenge induced sputum and urine test.
Results: Pool-based athletes had better lung function (FEV1 = 110% vs 102% predicted, mean difference = 8.200 ± 2.339, P = 0.0006 and FVC = 5.64 vs 4.75 L, mean difference = 0.8855 ± 0.1951, P < 0.0001) and more marked airways hyper-reactivity (AHR) (percent drop in FEV1 after EVH = 18.14 vs 11.47, mean difference = 6.67, 95% confidence interval = 2.89-10.53, P = 0.0009). More pool-based athletes had a positive EVH test (72% pool vs 39% nonpool), but there was no difference between groups with respect to eosinophilic inflammation (sputum eosinophil percentage: pool = 2.07, nonpool = 2.28, P = 0.77; exhaled nitric oxide: pool = 32.54, nonpool = 35.77, P = 0.60). Athletes with a positive EVH test had less neutrophilic inflammation (P = 0.01) and more epithelial cells (P = 0.03) in their sputum.
Conclusions: Pool-based endurance athletes have greater evidence of AHR than non-pool-based athletes but no evidence of greater eosinophilic airway inflammation. Athletes who test positive on EVH are more likely to be eosinophilic and have higher levels of epithelial cells in their sputum.