Bronchodilator Response (BDR): Comparison of the ERS/ATS Technical Standard on Interpretative Strategies for Routine Lung Function with BTS/NICE Disease-Specific Guidelines

<bold>Background:</bold> Multiple methods for measuring BDR have been described. The BTS/NICE BDR (12% and 200mL change from baseline value) is used in United Kingdom (UK) guidelines but international guidance is increasingly preferring the ERS/ATS BDR (10% change from predicted value) to reduce gender and size bias and a revised level of significance based on survival. This work by international societies conflicts with current disease-specific guidelines used in UK. <bold>Aim:</bold> To evaluate the ERS/ATS recommendations for BDR against current BTS/NICE UK guidelines. <bold>Methods:</bold> 1330 consecutive patients referred into a respiratory physiology service (April to Nov. 2023) for the assessment of BDR were reviewed against the ERS/ATS and BTS/NICE BDR criteria. <bold>Results:</bold> Using the ERS/ATS BDR method, 240 patients (18.0%) had a positive BDR for Forced Expiratory Volume in 1 second (FEV₁) and/or Forced Vital Capacity (FVC) vs 257 patients (19.3%) when using BTS/NICE. Using the ERS/ATS criteria, 75 (5.6%) patients were reclassified, 29 (2.2%) newly positive (55.2% female) and 46 (3.5%) no longer positive (67.4% male) in FEV₁ and/or FVC. <fig><object-id>erj;64/suppl_68/OA4586/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusion:</bold> The approach to BDR assessment can impact diagnosis and treatment. Clinicians should be mindful of criteria variations. The unified international approach among scientific societies is required to resolve conflicting documents.