Fractional exhaled nitric oxide during acute viral bronchiolitis and future asthma at the age of four years

Abstract

Background: Acute viral bronchiolitis (AB) in infants is a risk factor for recurrent wheezing and asthma later in life. Fractional exhaled nitric-oxide (FeNO) is a marker of eosinophilic airway inflammation. High FeNO levels may predict asthma. Aim: To investigate whether FeNO levels during the acute phase and convalescence of AB are associated with the occurrence of asthma at the age of 4 years. Methods: Children (0-2 years) admitted to the emergency department with AB were recruited. The following data was collected: family and patient9s history, disease severity and FeNO levels. Nasal secretions were sampled and real-time PCR for respiratory viruses was performed. FeNO levels and the occurrence of wheezing episodes were re-assessed 2 and 6 months after AB. At age of 4 years, all children were evaluated for asthma and wheezing history using a validated parental questionnaire. Results: A total of 115 children with AB were recruited, most had RSV infection (alone or as co-infection with another virus). Fifty-seven children (49.6%) completed asthma evaluation at the age of four. 38% had current asthma and 26% had previous recurrent wheezing but were asymptomatic for at least 12 months. Only 36% did not suffer from any wheezing episode after the AB. Compared to other viruses, AB due to RSV was not associated with a higher risk of future asthma. FeNO levels at acute stage or during 6 months follow-up did not predict asthma at the age of four. Conclusions: A high proportion of infants with AB caused by a variety of viruses have asthma at 4 years of age. FeNO levels during or after AB did not predict future asthma in this population.