Impact of ERS/ATS changes in bronchodilator reversibility calculations on paediatric asthma diagnosis

<bold>Background:</bold> Demonstration of bronchodilator reversibility (BDR) is central to most asthma guidelines to confirm asthma. Previous ERS/ATS spirometry interpretation guidelines (Pellegrino 2005), and most current asthma guidelines, recommend a relative increase in FEV1 of ≥12% from baseline as significant BDR. Recently, alternative calculations have been suggested; FEV1 increase relative to predicted value (Stanojevic 2021), or FEV1 z-score change (Quanjer 2017). However, there is no corresponding consensus from asthma guidelines. <bold>Aim:</bold> To explore the impact of BDR calculation on paediatric asthma diagnosis. <bold>Method:</bold> Spirometry and BDR were performed in 180 children (5-16 years) with symptoms of asthma without a diagnosis. BDR was calculated for each participant. They were categorised as positive or negative using methods and thresholds recommended by Pellegrino, Stanojevic, and Quanjer. <bold>Results:</bold> Compared with Pellegrino, concordance was 169/180 (94%) with Stanojevic and 146/180 (81%) with Quanjer. Based on the same test, 10-16% of children diagnosed with asthma using Pellegrino would not have asthma confirmed using alternative methods. Furthermore, 5-20% of children who did not have asthma confirmed using Pellegrino, would have using alternative calculations. <fig><object-id>erj;64/suppl_68/OA3660/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusion:</bold> The BDR calculation used has important clinical implications for asthma diagnosis in children. Consensus on which to use is needed.