[Usefulness of selected tests in the diagnosis of exercise induced bronchoconstriction].

BACKGROUND

Indirect airway challenge tests are commonly used in the diagnosis of exercise-induced bronchoconstriction (EIB), defined as a post-exercise decrease in FEV(1) ≥ 10%. The aim of this study was to evaluate the diagnostic value of bronchial hyperreactivity tests in the diagnosis of EIB.

METHODS

Forty two subjects were allocated to 3 groups: A - 19 steroid naive asthma patients; D - 11 no-asthma patients reporting symptoms suggestive for EIB (dyspnea, wheeze 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 cutoff of ≥ 10% or ≥ 15% decrease in FEV1 post exercise EIB was diagnosed in 47% and 37% of asthma patients, respectively; 27% of subjects in group D and in none of controls, irrespectively of the ΔFEV(1) criterion.

RESULTS

The analysis of 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. dyspnea, wheezes and cough provoked by exercise) with a sensitivity of 70%, specifity of 94%, PPV of 78%, NPV of 91% and LR of 11.2.

CONCLUSIONS

Symptoms suggestive of EIB do not have acceptable sensitivity and specifity for the diagnosis of exercise-induced bronchoconstriction. The most useful measure to diagnose EIB is a combination of typical symptoms of EIB with positive challenge to AMP.