Dose-related bronchodilator response in obstructive asthmatic children

Abstract Purpose Spirometry with bronchodilator responsiveness (BDR) testing is central to pediatric asthma diagnosis. Despite guideline recommendations of 200–400 µg short-acting beta agonist (SABA), evidence suggests that these doses may lack sensitivity. We evaluated whether a 600-µg dose improves BDR detection in children with baseline airflow limitation compared to the standard 400 µg. Methods We retrospectively analyzed spirometry records from the ACCESS database at Armand Trousseau Hospital (Paris, France). Children ≤ 18 years with confirmed asthma and baseline airflow limitation (FEV 1 /FVC z-score <-1.64) were included. Positive BDR was defined as a post-SABA increase in FEV 1 and/or FVC > 10% predicted. Multivariable mixed-effects logistic regression accounted for repeated measurements and potential confounders. Results A total of 1162 spirometry tests from 682 subjects were analyzed. BDR was detected in 69.2% of tests using 600 µg versus 51.3% with 400 µg (p < 0.001). In multivariate analysis, 600 µg (OR 2.73, 95%CI 1.94–3.85) and Afro-Caribbean ancestry (OR 2.96) were the strongest independent predictors of positive BDR. Additional independent predictors included poor asthma control (OR 1.99) and male sex (OR 1.44). Ongoing antiasthmatic treatment (OR 0.56) and increasing age (OR 0.82) were negatively associated with BDR. Results were consistent across spirometry quality grades. Conclusion In asthmatic children with airflow limitation, 600 µg SABA dose significantly increases BDR detection compared to 400 µg, suggesting that standard dosing may underestimate reversibility. Prospective studies are warranted.