Diagnostic value of bronchoprovocation challenge with adenosine monophosphate versus exercise testing in early diagnosis of asthma.

BACKGROUND: Airway hyperresponsiveness (AHR) is a characteristic feature of bronchial asthma and is diagnosed using direct and indirect bronchoprovocation tests. The diagnosis of AHR is a challenge in symptomatic patients with a normal baseline prebronchodilator spirometry and postbronchodilator spirometry. Exercise-induced asthma or exercise-induced bronchoconstriction (EIB) is a distinct form of AHR. There is no single test that is sufficient to exclude AHR in symptomatic military personnel with normal spirometry. This study was conducted to compare the diagnostic value of indirect bronchoprovocation test using inhaled adenosine monophosphate (AMP) and exercise challenge test (ECT) in the diagnosis of EIB.
METHODS: A crossover study was conducted with consecutive sampling of patients presenting with symptoms suggestive of asthma and with normal spirometry results who were subjected to both ECT and bronchoprovocation test using inhaled AMP on separate days.
RESULTS: Forty participants were recruited (the mean age: 25 yrs, 100% male). The commonest presentation was breathlessness on exercise (55%). With exercise alone, 40% tested positive for AHR, while with AMP alone, the positivity increased to 53%, and the difference was statistically significant (p= 0.03). Exercise alone failed to detect 8 cases that tested positive for AHR by inhaled AMP challenge.
CONCLUSION: Indirect bronchoprovocation test using inhaled AMP may be used to diagnose AHR in conditions in which exercise challenge testing is not available or the patient is unable to complete ECT.