[Contribution of exhaled nitric oxide measurements to abbreviated bronchial challenge test protocols].
OBJECTIVE
The bronchial challenge test is commonly used to diagnose asthma but it is a tedious, time-consuming procedure. Although in recent years, several shortened methods have been proposed, it has been shown that they can give rise to exaggerated bronchoconstriction. The aims of the present study were a) to determine the frequency of exaggerated bronchoconstriction in patients with asthma following the application of a shortened bronchial challenge test, and b) to determine if the fraction of exhaled nitric oxide (FENO) can be used to predict the onset of exaggerated bronchoconstriction.


METHODS
We performed a prospective study of 210 patients with asthma in whom FENO levels were measured in accordance with the abbreviated protocol recommended by the European Respiratory Society (ERS). Exaggerated bronchoconstriction was defined as a decrease of more than 20% in forced expiratory volume in 1 second after the first challenge, after a skipped dose, or after administration of saline. A receiver operating characteristic (ROC) curve was generated to determine the best FENO cutoff value for predicting exaggerated bronchoconstriction. The pretest probability of developing exaggerated bronchoconstriction was also calculated using Bayes' theorem.


RESULTS
The frequency of exaggerated bronchoconstriction in our series was 30%. Patients who developed exaggerated bronchoconstriction had significantly higher FENO levels than those who did not (32.6 vs 16.2 parts per billion [ppb]). The chosen FENO cutoff of 19.5 ppb had a sensitivity of 80%, a specificity of 77%, and a negative predictive value of 88%. The area under the ROC curve was 0.83 (95% confidence interval, 0.77-0.89).


CONCLUSIONS
The abbreviated bronchial challenge test recommended by the ERS led to exaggerated bronchoconstriction in 30% of the patients studied. FENO measurements could possibly be used to identify patients at increased risk of exaggerated bronchoconstriction. The shortened challenge test can be performed safely in individuals with a FENO of <19.5 ppb.
Lloris Bayo
Amparo
A
Servicio de Neumología, Hospital Universitario La Fe, Valencia, España. amparolloris@yahoo.es
Perpiñá Tordera
Miguel
M
Martínez Pérez
Encarnación
E
Macián Gisbert
Vicente
V
D000328:Adult; D001249:Asthma / Q000175:diagnosis*; D001944:Breath Tests; D001985:Bronchial Provocation Tests / Q000379:methods*; D002985:Clinical Protocols; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D011446:Prospective Studies
D009569:Nitric Oxide