A new study has identified four distinct clinical patterns of bronchiolitis in infancy, which are also predictive of the asthma risk.¹

For this study, researchers from US, France and Finland analysed data from three multi-center, multi-year prospective cohort studies namely MARC-30 USA, MARC-35, MARC-30 Finland (performed as part of the Multicenter Airway Research Collaboration [MARC]) of infants who had been admitted to hospitals with severe bronchiolitis. A total of 3081 infants were included in the present study. The research objectives were firstly characterization of severe bronchiolitis and then to investigate if these profiles had any association with the risk for developing asthma.

After analysis of data, four clinically distinct profiles of infants hospitalized for bronchiolitis were determined.

The features of Profile A were a history of breathing problems and eczema, high prevalence of rhinovirus and non–respiratory syncytial virus (non-RSV) infection; 13% (n=388) infants fit this profile. The second group, Profile B had the largest number of infants (34%; n=1064) and their clinical presentation had the hallmark symptoms of wheezing and cough found in classic RSV-induced bronchiolitis

The severely ill comprised the third group, Profile C with 993 infants (32%) had severe retraction at presentation, their oral intake was inadequate and they also stayed in the hospital for a longer duration. Profile D included the least ill infants (32%; n = 993) with little history of breathing problems with no or mild retraction, but inadequate oral intake.

Overall, the risk for developing asthma was 23% by 6 or 7 years of age.

When these distinct profiles were examined for their association with ensuing risk for developing asthma, infants with profile A were found to be most at risk for developing asthma with a 2.5-fold increased risk versus the typical bronchiolitis profile in the B group of infants.

A third objective of the study was to develop a decision rule utilizing four factors (RSV infection, history of breathing problems, history of eczema, and parental history of asthma)  to predict the profile at highest risk for asthma. These four factors were strongly predictive of infants (profile A) at the highest risk for developing asthma. Infants with profile A were likely to be older and were more likely to have parent/s with a positive history of asthma; no infant in this group had solo-RSV infection.

Viral bronchiolitis during infancy is a major risk factor for childhood asthma. This study has demonstrated the heterogeneous clinical profile of bronchiolitis illustrating the complex mechanisms of the disease by identifying four distinct clinical profiles, which were at different risks for developing asthma later on. It has also validated a prediction rule to identify the profile which was at the highest risk for developing asthma. This study provides evidence-based guidance to treating physicians for earlier identification of infants at risk of asthma and to develop “profile-specific preventive strategies for asthma” such as “prophylaxis for severe viral infection”.

Reference

1. Fujiogi M, et al. Identifying and predicting severe bronchiolitis profiles at high risk for developing asthma: Analysis of three prospective cohorts. E Clinical Medicine. 2022 Jan 4;43:101257. doi: 10.1016/j.eclinm.2021.101257