Usefulness of Selected Tests in the Diagnosis of Exercise-Induced Bronchoconstriction

Introduction: Indirect airway challenge tests are commonly used in the diagnostics of exercise-induced bronchoconstriction (EIB), defined as a post-exercise decrease in FEV₁ ≥ 10%. The aim of this study was to evaluate the diagnostic value of bronchial hyperreactivity tests in the diagnosis of EIB. Material and methods: Forty-two subjects were allocated into 3 groups: A—19 steroid-naive asthma patients; D—11 non-asthma patients reporting symptoms suggestive of EIB (dyspnoea, wheezing, and cough provoked by exercise); and K—12 healthy controls. Subjects filled a questionnaire regarding symptoms related to exercise and underwent: inhaled bronchial challenge to methacholine (Mch), adenosine 5’-monophosphate (AMP), and exercise challenge on a treadmill. With a cut-off of ≥ 10% and ≥ 15% decrease in FEV₁, EIB was diagnosed in 47% and 37% of asthma patients, respectively. Exercise-induced bronchoconstriction was found in 27% of subjects in group D and in none of the controls, irrespectively of the FEV₁ criterion. Results: The analysis of the questionnaire revealed that a single symptom cannot be used to predict EIB. Symptoms occurring after termination of exercise, but not during exercise, characterize EIB more precisely. The analysis showed that the most useful measure to diagnose EIB can be a combination of bronchial challenge to AMP and typical symptoms of exercise-induced bronchoconstriction (i.e., dyspnoea, wheezing, and coughing provoked by exercise) with a sensitivity of 70%, specificity of 94%, PPV of 78%, NPV of 91%, and LR of 11.2. Conclusions: Symptoms suggestive of EIB do not have acceptable sensitivity and specificity for the diagnosis of exercise-induced bronchoconstriction. The most useful measure to diagnose EIB is the combination of typical symptoms of EIB with a positive challenge to AMP.