Does the measurement of fractional exhaled nitric oxide have a role in the detection of exercise-induced bronchoconstriction in athletes?

Aim: Fractional exhaled nitric oxide (FeNO) is an indirect marker of airway inflammation, recommended for the assessment and management of asthma (1). The role of FeNO in detecting exercise-induced bronchoconstriction (EIB) and monitoring respiratory health in athletes has however yet to be established. The aim of this pilot study was therefore to evaluate the value of FeNO in detecting EIB in a screened cohort of athletes. Method: Fifty-three endurance trained athletes (male: n = 36) (age: 34 ± 10 years) performed baseline FeNO and spirometry pre-and-post a eucapnic voluntary hyperpnoea challenge (EVH) (2). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for established FeNO thresholds: (intermediate [>25ppb] and high [>50ppb]) (1) and evaluated against objective evidence of EIB: (EVH diagnostic cut-off [-10% ΔFEV1 at two consecutive time-points] (3) and [-15% ΔFEV1 at one time-point]) (2). The diagnostic accuracy of FeNO was calculated using receiver operating characteristics area under the curve (ROC-AUC). Results: All athletes had normal resting lung function (>80% FEV1 pred). The prevalence of EIB was 19% (-10% ΔFEV1) and 15% (-15% ΔFEV1) (mean ΔFEV1 = -8.2% ± 9.2). FeNO values >25ppb and >50ppb were observed in 45% and 17% of the cohort, respectively. ROC-AUC for FeNO was 75% (-10% ΔFEV1) and 83% (-15% ΔFEV1). Sensitivity, specificity, PPV and NPV are presented in Table 1. Conclusion: FeNO is a simple tool that has an established role in the assessment of airway inflammation in athletes. FeNO >50 had good specificity (93%) for a positive EVH test; however given the poor predictive values, our findings indicate that FeNO should not be employed as a substitute for indirect bronchoprovocation for diagnostic purposes. Future research is required to establish normative values and determine the role of FeNO in modifying the treatment of EIB in athletes.

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