Background

The heterogeneity of bronchiolitis may imply or reflect a different predisposition to respiratory sequelae.

Objective

Our aim was to investigate whether, among infants hospitalized with bronchiolitis, different clinical profiles extracted by latent class analysis(LCA) are associated with different risks of wheezing.

Methods

Over fifteen consecutive epidemic seasons(2004-2019), we prospectively enrolled infants<1 year hospitalized for the first episode of bronchiolitis in a single tertiary hospital. A detailed clinical questionnaire was filled for each infant. LCA was applied to differentiate bronchiolitis phenotypes, and after hospital discharge, a phone interview was performed annually to record the presence of wheezing episodes. Adjusted multivariate regression analyses were run to investigate the risk of wheezing during seven years follow-up according to clinical phenotypes.

Results

LCA performed on 1312 infants resulted in a three-class model. Profile 1(65.5%): moderate bronchiolitis; Profile 2(6.1%): severe bronchiolitis; and Profile 3(28.4%): bronchiolitis infants with high eosinophils blood count. At one year of follow up, about 50% of children presented wheezing in each profile. Compared to profile 1, the adjusted OR of having wheezing episodes was significantly higher in Profile 2 at two, three, and four years of follow-up. At seven-years, Profile 3 had an adjusted OR=2.58, higher than profile 2 (adjusted OR=2.29).

Conclusions

LCA clearly identified a “moderate”, “severe” and “high eosinophils blood count” bronchiolitis. During the first four years after bronchiolitis, the “severe” profile showed the higher risk of wheezing, but after seven years this risk seems higher in the “high eosinophils blood count” group.

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