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Eosinophil Count Determines Steroids or Not for Asthma?

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Written by Samuel Rouleau

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In this trial, randomizing adult patients admitted for asthma exacerbation to shorter duration of steroids (3 days or 5 days) based on their peripheral eosinophil counts was non-inferior to the control group (5 days of steroids).

Low eosinophils = shorter steroids in asthma
Oral corticosteroids (OCS) have been a mainstay of asthma treatment, but prolonged corticosteroid use comes with significant consequences. This trial enrolled adult patients hospitalized for asthma exacerbations (non-ICU). Patients were enrolled to eosinophil-guided OCS (n=55) or usual care (n=55). Usual care was treatment with 5 days of prednisolone (0.5 mg/kg day, 20-50 mg). In the eosinophil-guided group, patients with peripheral blood eosinophil counts < 300 cells/μL were treated with 3 days of prednisolone. If eosinophil counts were ≥ 300 cells/μL, they were treated with 5 days of prednisolone.

In the intervention arm, 66 (60%) of the patients had “eosinophilic” asthma based on peripheral eosinophil counts and received 5 days of prednisolone. The primary outcome of treatment failure occurred in 6 patients (10.9%) in the eosinophil-guided group compared to 4 patients (7.3%) in the usual care group, which was not statistically significant and met the 20% non-inferiority mark. There were no deaths or decompensation that required positive pressure ventilation or intubation. Each treatment failure was for an extension of OCS duration. Out of the 10 patients in the trial who failed treatment and needed longer duration of OCS, 7 (70%) had eosinophils ≥ 300 cells/ μL.

How will this change my practice?
This study is exciting and will certainly prompt a larger trial. ED care for asthmatics must move beyond albuterol and a prednisone prescription.

  • When I discharge ED patients with asthma exacerbations, I will consider decreasing the duration of OCS on an individual basis.
  • They must have blood eosinophils < 300 and be able to reliably follow up (preferably with a PCP or the ability to return to the ED easily).
  • In general, we see a lot of asthma in the ED, and we should make sure our practices reflect updated guidelines (i.e. SMART therapy).

Source 
Blood eosinophil-guided systemic corticosteroid duration in adults hospitalised for asthma exacerbation: a randomised, controlled, open-label, non-inferiority trial. Thorax. 2025 Dec 3:thorax-2025-223961. doi: 10.1136/thorax-2025-223961. Epub ahead of print. PMID: 41339088.

View Critical Appraisal

Critical Appraisal

Title: Blood eosinophil-guided systemic corticosteroid duration in adults hospitalised for asthma exacerbation: a randomised, controlled, open-label, non-inferiority trial.
Background: Asthma exacerbations are a significant cause of morbidity and healthcare costs. Systemic corticosteroids are standard treatment, but optimal duration is unclear. Biomarker-guided approaches may reduce unnecessary exposure.
Study Question: Can blood eosinophil counts safely guide the reduction of systemic corticosteroid exposure in hospitalized asthma exacerbations?
Study Design: Randomized, controlled, open-label, noninferiority trial
Population: Adults aged ≥21 years hospitalized for asthma exacerbation, not on systemic corticosteroids within 7 days prior to admission
Intervention: Eosinophil-guided corticosteroid duration (3 days if eosinophils <300 cells/μL; 5 days if ≥300 cells/μL)
Comparison: Usual care with 5 days of prednisolone
Primary Outcome: Noninferiority of treatment failure rates (extension of steroid duration, mechanical ventilation, or death)
Secondary Outcomes: Length of stay, cumulative corticosteroid dose, additional steroid bursts, emergency visits, ACQ5 score changes
Key Statistics: Treatment failure rate difference of 3.6% (95% CI −8.9% to 16.2%), p=0.0004 for cumulative dose difference in noneosinophilic vs eosinophilic patients
Results: Eosinophil-guided therapy was noninferior to usual care with similar treatment failure rates and reduced steroid exposure in noneosinophilic patients.
Risk of Bias – RoB 2:
  • Randomization Process: Randomization was adequately performed with concealed allocation.
  • Deviations from Intended Interventions: Open-label design may have influenced treatment adherence and outcome assessment.
  • Missing Outcome Data: Follow-up was high with minimal missing data.
  • Measurement of the Outcome: Open-label design may have introduced bias in subjective outcome measures.
  • Selection of the Reported Result: All prespecified outcomes were reported.
Take Home: Blood eosinophil counts can guide corticosteroid duration in asthma exacerbations, reducing exposure without compromising safety.
This critical appraisal is generated using a structured framework applied to the full text of the original article and is presented separately from the physician’s commentary.

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