Background: The interpretation of bronchodilator responsiveness (BDR) as per new ERS/ATS criteria has been not yet evaluated in Indian children with asthma [1].

Objective: The primary objective was to compare BDR interpretation by old versus new ERS/ATS criteria in children with asthma.

Methods: We enrolled children (5-18 years) with newly diagnosed bronchial asthma on a clinical basis. Pulmonary function test (PFT) was performed as per the ERS/ATS recommendation[2]. PFT was repeated 10-15 minutes after 400 mcg of MDI salbutamol. A ?12 % increase in Forced Expiratory Volume in one second (FEV1) or Forced Vital Capacity (FVC) by old criteria [{(post- pre)/pre} x100], while >10% change in FEV1 or FVC by new criteria [{(post- pre)/predicted} x100] were considered positive BDR. The Global Lung Function Initiative (GLI) 2012 reference equation was used for predictive values.

Result: Ninety children were included, median (IQR) age of 10 (8, 13) years, and 61 (67.8%) were male. BDR with FEV1 was positive in 81 (90%) children by old criteria, while in 72 (80%) by new criteria. BDR with FVC was positive in 52 (57.8%) children by old criteria, while only in 41 (45.5%) by new criteria. There is moderate agreement (87.8%) between the two criteria using FEV1, ? = 0.52 (95% CI, 0.33-0.72), p <0.001, and good agreement using FVC, ? = 0.75 (95% CI, 0.55 ? 0.95), p <0.001.

Conclusion: The new ERS/ATS criteria of BDR testing appear promising in children with clinically diagnosed asthma. However, we observed more children showed positive BDR testing by old criteria compared to new criteria. There is a further need to validate new criteria in asthmatic children in different populations.