FeNO Predicts Exacerbation Risk in Asthma and COPD, Suggests Research
Netherlands: Researchers have discovered in a new study that higher baseline blood eosinophil counts were associated with an increased risk of exacerbations over one year in patients with asthma. Elevated baseline fractional exhaled nitric oxide (FeNO) levels were linked to greater odds of oral corticosteroid-treated exacerbations in patients with asthma and asthma-COPD overlap, while paradoxically being associated with a lower overall exacerbation risk in patients with COPD. These findings highlight the differing prognostic roles of eosinophils and FeNO across obstructive airway diseases.
The findings are from the multinational NOVELTY study, published in Thorax, in which Susan Muiser and colleagues investigated whether blood eosinophil counts and FeNO levels could predict future exacerbations in patients with asthma, COPD, and asthma-COPD overlap.
The analysis included 4,319 patients for eosinophil assessment and 7,770 patients for FeNO assessment. Baseline clinical characteristics, biomarker levels, lung function, and exacerbation history were recorded, and patients were followed for one year under routine clinical care.
The researchers found that higher baseline eosinophil counts were associated with an increased risk of exacerbations in asthma, with each doubling of the eosinophil count linked to a 9% higher exacerbation rate. A similar, though non-significant, trend was observed in COPD. When both biomarkers were analyzed together, elevated eosinophil levels independently predicted exacerbation risk in asthma and COPD.
Key findings from the study included:
- Higher baseline eosinophil counts were associated with an increased risk of exacerbations in asthma.
- Elevated FeNO levels were linked to a lower overall risk of exacerbations in COPD.
- In asthma, higher FeNO levels were associated with greater odds of exacerbations treated only with oral corticosteroids.
- Higher FeNO levels were also linked to increased odds of oral corticosteroid-treated exacerbations in patients with asthma-COPD overlap.
- In asthma, elevated FeNO was associated with lower odds of exacerbations treated only with antibiotics.
- When both biomarkers were analyzed together, higher eosinophil counts and lower FeNO levels independently predicted exacerbation risk in COPD.
The researchers found that FeNO showed different associations with exacerbations across asthma, COPD, and asthma-COPD overlap, indicating that eosinophils and FeNO may offer complementary insights into disease risk. They suggested that evaluating specific exacerbation subtypes could improve personalized treatment decisions.
The study was limited by physician-assigned diagnoses, potential treatment influences from biomarker availability, and possible recall bias in patient-reported exacerbation data. Overall, the findings support the use of blood eosinophils and FeNO as complementary biomarkers to help predict exacerbation risk and guide individualized management in obstructive airway diseases.
Reference:
Muiser S, Müllerová H, Belton L, et alAssociation of blood eosinophils and exhaled nitric oxide with exacerbations in patients with asthma, COPD and asthma+COPD: the NOVELTY study. Thorax Published Online First: 21 April 2026. doi: 10.1136/thorax-2025-223646
Next Story