Fractional exhaled nitric oxide in the assessment of exercise-induced bronchoconstriction: a multicentre retrospective analysis of UK-based athletes

Abstract

Copyright © the authors 2022 Background: Exercise-induced bronchoconstriction (EIB) is a condition characterised by temporary lower airway narrowing that occurs in association with physical activity. FeNO is an indirect biomarker of type 2 airway inflammation that has an established role in the assessment of asthma.

Aims: To evaluate the value of FeNO in the assessment of EIB.

Method: Multicentre retrospective analysis. Four hundred and eighty-eight athletes (male: 76%) performed baseline FeNO and spirometry pre-and-post eucapnic voluntary hyperpnoea (EVH). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for established FeNO thresholds: intermediate (≥25ppb) and high (≥40 ppb and ≥50ppb) and evaluated against objective evidence of EIB (≥10% fall in FEV1). 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). Despite this, 41% had a post-EVH fall in FEV1 consistent with EIB. FeNO values ≥25ppb, ≥40ppb and ≥50ppb were observed in 42%, 23% and 17% of the cohort, respectively. ROC-AUC for FeNO was 65%. Sensitivity, specificity, PPV and NPV are presented in Table 1.

Conclusions: FeNO ≥40 ppb provides good specificity, i.e., ability to rule-in a diagnosis of EIB. However, due to the poor sensitivity and predictive values, FeNO should not be employed as a replacement for EVH.