Abstract Rationale Recent studies suggest that blood eosinophils (BEC) and fraction of exhaled nitric oxide (FeNO) have significant weight in prognostication of future asthma exacerbations for participants in asthma treatment clinical trials and severe asthma cohort studies enrolling those with uncontrolled asthma. The predictive properties or T2 biomarkers and clinical factors for exacerbation risk in routine subspecialty care is less understood. Methods The REal-world and Genomic data-based Asthma Insights through Network analysis (REGAIN) study was an 18-month prospective, observational study of asthma patients enrolled from clinical subspecialty programs. Prespecified groups enrolled according to T2 biomarkers, treatment, and asthma control included a majority with well-controlled symptoms at enrollment. We assessed the prognostic value of FeNO and BEC on asthma exacerbation risk. Clinical measures predictive of exacerbations in published studies were also evaluated. Analyses were performed for those on stable asthma therapy with measures available for the followup period (n = 426). Univariate and multivariate regression analyses were conducted to investigate interactions between Asthma Control Test (ACT) score, asthma exacerbations in the prior year, FEV1, maximal historical BEC, baseline BEC, FEV1, maximal BEC, maximal historic FeNO, baseline FeNO, and GINA step therapy level on asthma exacerbation risk (defined as requiring at least 3 days of corticosteroids). Results There were no differences in age, BMI, maximum BEC, maximum FeNO, baseline FeNO, or follow-up duration in those with or without an exacerbation during follow-up. Those who had an asthma exacerbation during the follow-up period had higher GINA step therapy (p 0.001), lower baseline ACT (p 0.001), and lower FEV1 (p = 0.003) Multivariate regression analysis of annualized asthma exacerbation rates showed a moderate correlation with prior exacerbation in the last 12 months (RR 3.19 (95% CI 1.74-5.87), p 0.001) and a weak correlation with baseline ACT score (RR 0.87, (95% CI 0.83-0.92), p 0.001). We did not identify a significant correlation with maximum or baseline BEC, maximum or baseline FeNO, baseline FEV1, or GINA step therapy. Conclusions In a cohort of patients in specialty care with largely well-controlled asthma and enriched in type 2 low participants, maximum and current BEC and FeNO may have less weight in predicting future asthma exacerbations than current ACT score and prior exacerbation history. Further research is needed in real-world cohorts with heterogenous asthma severity, control, and endotype to assess the contribution of inflammatory biomarkers in predicting future asthma exacerbations under conditions of routine clinical care. This abstract is funded by: Sanofi
Duong et al. (Fri,) studied this question.