RT Journal Article SR Electronic T1 Higher exhaled nitric oxide levels in infancy is associated with less bronchiolitis and fewer adverse respiratory outcomes in the first year of life JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP PA3069 DO 10.1183/13993003.congress-2021.PA3069 VO 58 IS suppl 65 A1 Carla Rebeca Da Silva Sena A1 Ediane De Queiroz Andrade A1 Patricia De Gouveia Belinelo A1 Elizabeth Percival A1 Ben Prangemeier A1 Chris O’Donoghue A1 Sandrine Terry A1 Tanya Burke A1 William Gunning A1 Vanessa E Murphy A1 Paul D Robinson A1 Peter D Sly A1 Peter G Gibson A1 Adam Collison A1 Joerg Mattes YR 2021 UL http://erj.ersjournals.com/content/58/suppl_65/PA3069.abstract AB Introduction: Nitric oxide (NO) plays a role in immune responses to pathogens. Exhaled NO (eNO) is used as a noninvasive biomarker of airway inflammation in older children with asthma. However, the role for eNO in infancy has not been completely ascertained.Aim: To investigate the association between eNO at 6 weeks of age and the incidence of bronchiolitis and respiratory symptoms in the first 12 months of life.Methods: Infants at 6 weeks of age, born to mothers with asthma in pregnancy from the Breathing for Life Trial were assessed to measure eNO using a rapid-response chemiluminescence analyzer (CLD88;EcoMedics) interpolated to an expiratory flow of 50mL/s and normalized using square root (sq). We applied a standardised parent completed questionnaire at 12 months of age to investigate bronchiolitis and symptoms. Associations were investigated by multivariate linear and Poisson regression models.Results: 184 babies had valid eNO measurements at 6 weeks of age, 125 (68%) had data at 12 months of age collected. Higher eNO was associated with less respiratory symptoms during the first weeks of life (n=155, ß-coefficient:–0.62, p=0.028). Babies without an episode of bronchiolitis in the first year of life had significantly higher eNO (3.60 ppb vs 3.11 ppb, p=0.009). Risk incidence of bronchiolitis, wheeze, cold or flu, short-acting beta-agonist use, and recurrent bronchiolitis significantly decreased by 18% to 24% for every increase in sq eNO ppb in multivariate models.Conclusion: Infants with higher eNO levels at 6 weeks of age were significantly less likely to develop bronchiolitis and other respiratory symptoms at 12 months of age. In infancy, higher eNO levels may be a surrogate marker for more effective anti-viral immune responses.FootnotesCite this article as: European Respiratory Journal 2021; 58: Suppl. 65, PA3069.This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).