Questionnaire responses that predict airway response to hypertonic saline

Background: Airway hyperresponsiveness to hypertonic saline (HS) is associated with airway inflammation. We investigated if responsiveness to HS was predicted by asthma symptoms in the last 3 months. Objectives: To investigate if responsiveness to HS can be estimated by questionnaire items investigating asthma symptoms of the last 3 months. Methods: Six hundred and four patients with physician-diagnosed asthma being assessed for asthma severity were studied. Bronchial provocation with 4.5% saline was performed, and a questionnaire was administered. The response to 4.5% saline was reported as the provoking dose to causea 15% fall in the forced expiratory volume in 1 s FEV ₁ (PD ₁₅) and the response-dose ratio (RDR). Results: Based on the GINA guidelines, asthma severity was intermittent in 497 patients, mild in 107 patients, moderate in 3 patients and severe in 1 patient. A PD ₁₅ to 4.5% saline was recorded in 234 of the 604. Questions on self-recognition of asthma, dust as a trigger, food as a trigger, and frequency of bronchodilator use were significant predictors for a PD ₁₅, and currently taking steroids decreased the likelihood of a positive response to 4.5% saline. Using a multiple-linear regression model, a difference in the RDR could be calculated between those who answered positively compared with the reference group, who answered negatively. This difference could be used as a guide for predicting abnormal reactivity. An increase in RDR in response to 4.5% saline, compared with the reference group, was demonstrated in the presence of self-recognition of asthma severity, dust and cats as a trigger or use of bronchodilator during sleep hours. Conclusions: Because of the high positive predictive value of HS for identifying patients with asthma it might be that the need for bronchodilator use at night not only predicts airway hyperresponsiveness to HS, it also could reflect the severity of asthma.