Measures of lung function and inflammation in patients hospitalised with severe asthma attacks and 2 weeks later

<bold>Background:</bold> Severe asthma attacks (SAA) are often treated with systemic corticosteroids (SCS) without objective measures of airflow obstruction (AO). <bold>Aim:</bold> To describe lung function (LF) and inflammation (INF) in patients with SAA on hospital admission, and 2 weeks later. <bold>Methods:</bold> An observational, longitudinal clinical study describing LF and INF on admission for SAA (V1) and two weeks after discharge (V2). AO was defined using spirometry (SP) (FEV₁/FVC <0.7) or Forced Oscillation (FOT) (R5 >5 cmH2O). INF was defined as sputum eosinophils (SEC) >3%, blood eosinophils (BEC) >0.4 x10^9/L or exhaled nitric oxide (FeNO) >50 ppb. <bold>Results:</bold> 83 patients completed SP + FOT at V1. 35 (42%) had no AO on SP but 16 of these had AO on FOT meaning 19 (23%) had no AO on either measure. Only 5 of those without AO had raised INF (Table 1). <table-wrap><object-id>erj;64/suppl_68/PA4765/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>V1</td><td>Patients without AO (n= 19, 23%)</td><td>Patients with AO (n= 64, 77%)</td></tr><tr><td>Normal INF</td><td>14 (73%)</td><td>32 (50%)</td></tr><tr><td>Raised INF</td><td>5 (26%)</td><td>32 (50%)</td></tr><tr><td>SEC >3%</td><td>2 (11%)</td><td>12 (19%)</td></tr><tr><td>BEC > 0.4</td><td>3 (16%)</td><td>17 (26%)</td></tr><tr><td>FeNO > 25 ppb</td><td>9 (47%)</td><td>31 (48%)</td></tr><tr><td>FeNO > 50 ppb</td><td>4 (21%)</td><td>20 (31%)</td></tr><tr><td>Asthma mimics*</td><td>11 (58%)</td><td>25 (39%)</td></tr></tbody></table></table-wrap> Table 1.*i.e., Vocal cord dysfunction, dysfunctional breathing 47 patients completed V1+V2 of whom 37 (79%) had AO at V1; 22 (60%) of 37 with AO at V1 still had AO at V2 (Table 2). <table-wrap><object-id>erj;64/suppl_68/PA4765/T2</object-id><object-id>T2</object-id><object-id>t2</object-id><table><colgroup><col></col><col></col></colgroup><tbody><tr><td>V2</td><td>Patients with AO (n= 22, 60%)</td></tr><tr><td>Normal INF</td><td>14 (64%)</td></tr><tr><td>Raised INF</td><td>8 (36%)</td></tr><tr><td>SEC >3%</td><td>1 (5%)</td></tr><tr><td>BEC > 0.4</td><td>5 (23%)</td></tr><tr><td>FeNO > 25</td><td>9 (41%)</td></tr><tr><td>FeNO > 50</td><td>5 (23%)</td></tr></tbody></table></table-wrap> Table 2 <bold>Conclusion:</bold> 14, (17%) of patients admitted for SAA had no evidence of AO or raised inflammatory markers and most had a documented diagnosis of known asthma mimics. Point of care SP and FOT can help exclude a diagnosis of SAA, and potentially avoid the use of SCS treatment.