The Relationship of the Bronchodilator Response Phenotype to Poor Asthma Control in Children with Normal Spirometry

Objective To determine the relationship of poor asthma control to bronchodilator response (BDR) phenotypes in children with normal spirometry. Study design Children with asthma were assessed for clinical indexes of poorly controlled asthma. Pre- and post-bronchodilator spirometry were performed, and the percent BDR was determined. Multivariate logistic regression assessed the relationship of the clinical indices to BDR at >= 8%, >= 10%, and >= 12% BDR thresholds. Results There were 510 controller naive children and 169 on controller medication. In the controller naive population the mean age (+/- 1 SD) was 9.5 (3.4); 57.1% were male, 85.7% Hispanic. Demographics were similar in both populations. In the adjusted profile, significant clinical relationships were found particularly to positive BDR phenotypes >= 10% and >= 12% versus negative responses including younger age, (OR 2.0, 2.5; P < .05), atopy (OR 1.9, 2.6; P < .01), nocturnal symptoms in females (OR 3.4, 3.8; P < .01); beta(2) agonist use (OR 1.7, 2.8; P < .01); and exercise limitation (OR 2.2, 2.5; P < .01) only in the controller naive population. Conclusions The BDR phenotype >= 10% is significantly related to poor asthma control, providing a potentially useful objective tool in controller naive children even when the pre-bronchodilator spirometry result is normal. (J Pediatr 2011;158:953-9).