Fractional exhaled nitric oxide (FeNO) may be a reliable biomarker for predicting exacerbations in patients with moderate-to-severe asthma, according to recent research released as an abstract for the American Academy of Allergy, Asthma & Immunology (AAAAI) 2020 Annual Meeting.
“In uncontrolled, moderate-to-severe asthma patients, higher baseline FeNO levels were associated with higher severe asthma exacerbation rates over the subsequent 52 weeks, independent of standard clinical characteristics,” William Busse, MD, professor of allergy and immunology at the University of Wisconsin Medical School in Madison, Wisconsin, and colleagues wrote in their study abstract.
Busse and colleagues performed an analysis of patients with uncontrolled moderate-to-severe asthma in the phase 3 LIBERTY ASTHMA QUEST study who received dupilumab or a placebo for 52 weeks. In the trial, patients had asthma that was uncontrolled after failing two or fewer inhaled glucocorticoids and had at least one exacerbation within the least year. At baseline, patients had a forced expiratory volume in 1 second (FEV1) percent predicted ≤ 80%, and an Asthma Control Questionnaire (ACQ) score of 1.5 or greater. The researchers measured the annual severe asthma exacerbation rate of 620 patients in the placebo group using baseline FeNO levels in groups of < 25 parts per billion (PPB), 25 – < 50 PPB, and ≥ 50 PPB as well as baseline blood eosinophils in groups of < 150 cells/mL, 150 – < 300 cells/mL and ≥ 300 cells/mL.
“Fractional exhaled nitric oxide has emerged as an important biomarker for type 2 inflammation,” Busse and colleagues wrote in their abstract. “This study assessed the prognostic value of baseline FeNO levels, accounting for potential differences in baseline blood eosinophils and other clinical characteristics, for subsequent severe asthma exacerbations in uncontrolled, moderate-to-severe asthma patients receiving placebo in the dupilumab phase 3 QUEST study.”
After adjusting for baseline eosinophils and clinical characteristics, the exacerbation rate of patients with a baseline FeNO of ≥ 50 PPB was 1.54 times higher than patients with a baseline FeNO of < 25 PPB (95% CI, 1.11-2.14). Patients with a baseline FeNO of ≥ 50 PPB and eosinophils ≥ 300 cells/mL had 3.19 times the exacerbation rate of patients with baseline FeNO < 25 PPB and eosinophils < 150 cells/mL, after adjusting for clinical differences, the researchers said.
“[The] risk was particularly high in patients also having blood eosinophils ≥ 300cells/mL. These results suggest that FeNO, independently and in combination with blood eosinophils, identifies patients at increased risk of subsequent exacerbations,” Busse and colleagues concluded.