Phenotyping the responses to systemic corticosteroids in the management of asthma attacks (PRISMA)

Background Asthma attacks are heterogeneous. It is not known whether the response to oral corticosteroids (OCS) in acute asthma varies according to type 2 (T2) inflammatory biomarkers, blood eosinophil count (BEC) and fractional exhaled nitric oxide ( F ENO ). We aimed to explore the relationship between T2 biomarkers and response to OCS in acute asthma. Methods We conducted a longitudinal observational study of people experiencing an asthma attack evaluated before and after a 7-day OCS course. The primary outcome was post-bronchodilator change in forced expiratory volume in 1 s (FEV 1 ) according to ordinal BEC- F ENO three-group categories (T2-Low/Low: BEC <0.15×10 9 cells·L −1 and F ENO <25 ppb; T2-High/High: BEC ≥0.30×10 9 cells·L −1 and F ENO ≥35 ppb; T2-Mid: not meeting Low/Low or High/High criteria). A key secondary outcome was the change in Asthma Control Questionnaire-5 score. Exploratory outcomes included OCS-attributable adverse events. Results 53 people were enrolled, with 16 (30%) T2-Low/Low, 27 (51%) T2-Mid and 10 (19%) T2-High/High asthma attacks. Post-bronchodilator FEV 1 changes increased with combined BEC- F ENO elevation (p for interaction=0.007), peaking in the T2-High/High phenotype (0.390±0.512 L, p for trend<0.0001). Conversely, T2-Low/Low attacks showed nonsignificant FEV 1 changes (0.017±0.153 L). In univariable and multivariable analyses, only ordinal BEC- F ENO stratification, not symptoms nor FEV 1 , predicted subsequent post-bronchodilator FEV 1 improvement. All patients had improved Asthma Control Questionnaire-5 score, numerically peaking in the T2-High/High phenotype (−1.58±0.60, p for trend=0.08). All groups experienced similar OCS-attributable adverse events, with 33 patients (62%) reporting at least one event. Conclusions We found that objective improvement following OCS is confined to T2-High events. As in chronic asthma, greater T2 burden identifies a distinct clinical and therapeutic trajectory, whereas OCS‑related adverse events are uniformly distributed.