Value of the bronchodilator response in assessing controller naïve asthmatic children.

OBJECTIVE To define the bronchodilator response (BDR) cutoff point that best identified asthma to determine the frequency of abnormal spirometry results across severity. STUDY DESIGN Controller naïve children were evaluated with clinical criteria alone to establish a diagnosis of asthma and severity classification, then compared with the BDR, which was calculated as the percent change from the initial forced expiratory volume in 1 second. Receiver operator characteristic analysis determined the cutoff point for asthma diagnosis that gave the best combination of sensitivity and specificity. RESULTS Children with asthma (n = 346) and 51 children without asthma, aged 4 to 17 years, who met entry criteria for spirometry were identified. The mean BDR in asthmatics was 8.6% (95% CI, 7.5-9.8), compared with 2.2% (95% CI, 0.2-4.3) for non-asthmatics (P < .001). A BDR > or = 9% best differentiated these populations with a sensitivity rate of 42.5% and a specificity rate of 86.3%. Abnormal spirometry results, defined as a BDR > or = 9%, a forced expiratory volume in 1 second < 80% predicted, or both, ranged from 44.4% for mild intermittent bronchial asthma to 57.0% for severe persistent bronchial asthma. CONCLUSION Spirometric criteria that include BDR can potentially identify children who have clinically mild asthma and might benefit from controller therapy.