Association between FeNO, blood eosinophil counts (BEC) and exacerbation frequency in ICS treatment groups in COPD.

<bold>Introduction:</bold> In COPD, ICS lowers exacerbation frequency if stable state BEC ≥ 100 cells/µL. FeNO ≥ 20ppb predicts a better response to Dupilumab.1 The relationship between FeNO, BEC and exacerbation frequency is unclear. <bold>Aims:</bold> As part of the BECCOPD study (IRAS 285200), agreement between FeNO and BEC measurements in those with and without ICS treatment was examined. We also assessed exacerbation frequency in patients stratified by BEC and FeNO. <bold>Methods:</bold> Patients with stable COPD were recruited from primary and secondary care and had paired FeNO and BEC measured. FeNO was dichotomised at 20ppb and BEC at 100 cells/µL. Moderate and severe exacerbations were prospectively captured over one year. <bold>Results:</bold> 265 patients were included: mean (SD) age 71 (7) years; mean FEV1 55 (23) % predicted; 47% female; median (IQR) eMRCD 3 (3-4); 70% receiving ICS. Number of subjects (annual exacerbation rate) in each BEC/FeNO strata: <table-wrap><object-id>erj;64/suppl_68/PA3978/T1</object-id><object-id>T1</object-id><object-id>t1</object-id><table><colgroup><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td></td><td>BEC < 100</td><td>BEC ≥100</td></tr><tr><td>ICS use</td><td>FeNO <20</td><td>24 (1.6)</td><td>113 (2.4)</td></tr><tr><td>ICS use</td><td>FeNO ≥ 20</td><td><bold>6 (3.5)</bold></td><td>43 (2.6)</td></tr><tr><td></td><td></td><td>Level of agreement = 67/186 (36.0%)</td><td></td></tr><tr><td>No ICS use</td><td>FeNO < 20</td><td>7 (0.6)</td><td>40 (1.7)</td></tr><tr><td>No ICS use</td><td>FeNO ≥ 20</td><td><bold>6 (1.5)</bold></td><td>26 (1.3)</td></tr><tr><td></td><td></td><td>Level of agreement = 33/79 (41.8%)</td><td></td></tr></tbody></table></table-wrap> FeNO ≥20 was associated with a higher annual exacerbation rate among patients with BEC <, in both ICS treated and non-treated patients. <bold>Conclusion:</bold> FeNO was lower in patients using ICS. In patients with BEC < cells/µL, FeNO ≥20 was associated with more exacerbations, indicating a possible role of FeNO in guiding ICS therapy. <bold>Acknowledgements:</bold> The BECCOPD study is funded by GSK (GSK study number 214233) via the supported studies program. <bold>References:</bold> Bhatt et al. NEJM. 2023 Jul 20;389(3):205-214.