METHODS: A subset of TENOR-I patients (n=341) who enrolled in TENOR-II were assessed at one cross-sectional visit. Fractional exhaled Nitric Oxide (FeNO), peripheral blood eosinophils, basophils and total IgE levels were measured. Recent exacerbators (RE) had emergency room visits, hospitalizations, or steroid courses in the previous 12 months; non-recent exacerbators (NRE) did not.
RESULTS: Of the 300 TENOR-II patients with available data, 137 (45.7%) RE and 163 (54.3%) NRE were identified. RE and NRE patients had similar levels [SD] of FeNO (ppb) (32.3 [33.9] vs 27.8 [25.7]), basophils (µL) (53.1 [57.3] vs 48.3 [51.5]), eosinophils (µL) (195.4 [138.0] vs 202.7 [148.0]) and total IgE geometric means (IU/ml [95% CI]) (67.7 [47.8, 96.0] vs 73.1 [51.9, 103.0], respectively. RE patients were more likely than NRE to have a combination of high eosinophils (≥300µL) and high FeNO (≥25ppb) (14 [17.3%] vs 6 [8.6%], respectively), or a combination of high FeNO and high IgE (≥700 IU/mL) (6 [7.4%] vs 2 [2.8%] respectively).
CONCLUSIONS: FeNO, eosinophils, and IgE are laboratory measures which may be used in combination to identify patients with severe/difficult-to-treat asthma who may be at risk for exacerbations. This study reported higher percentages of RE patients with high Type2 biomarker combinations; small sample sizes limit further interpretation. However, findings suggest that combinations of biomarkers may reflect different aspects of Th2 inflammation in severe or exacerbation prone asthma.