Exercise-induced bronchospasm diagnosis in children. Utility of combined lung function tests.

BACKGROUND: The diagnosis of exercise-induced asthma or bronchospasm (EIB) is a complex dare in daily clinical practice. The consensus is that if bronchial hyper-responsiveness (BHR) is demonstrated in a patient with symptoms consistent with EIB, then that patient can be diagnosed with exercise-induced bronchospasm. The aim of this study was to determine which BHR test is the most efficient to diagnose EIB.

METHODS: Children under 16, without previous asthma diagnosis, or with stable asthma, complaining of asthma-like symptoms triggered by exercise were included. Bronchodilator, methacholine, mannitol, and exercise tests were performed on all patients, following established protocols. The performance of single and combined tests was determined.

RESULTS: Of 46 patients (median age: 12 yr, ranged 8-16 y.o.) were recruited, 30 (70%) previously diagnosed of asthma. BHR was detected in 93.47% of the children. The exercise challenge test detected BHR in 11 of 46 (23.90%) patients, bronchodilator test in 10 of 46 (21.70%), mannitol in 36 of 45 (80%) and methacholine in 41 of 45 (91.11%). The total number of patients with BHR was detected using a combination of the methacholine and mannitol tests. A combination of the methacholine test performed first, followed by the mannitol test, was able to diagnose BHR in 100% of children with lower number of tests (n = 45) than if the order was reversed (n = 50).

CONCLUSIONS: Methacholine and mannitol tests detect BHR in most children with suspected EIB. Bronchodilator and exercise tests show a low positivity rate. A combination of the methacholine test, followed by the mannitol test, gives the highest return to identify BHR in children for the diagnosis of EIB.