A clustering approach to identify severe bronchiolitis profiles in children

Abstract

Objective: Although bronchiolitis is generally considered a single disease, recent studies suggest heterogeneity. We aimed to identify severe bronchiolitis profiles using a clustering approach.

Methods: We analysed data from two prospective, multicentre cohorts of children younger than 2 years hospitalised with bronchiolitis, one in the USA (2007-2010 winter seasons, n=2207) and one in Finland (2008-2010 winter seasons, n=408). Severe bronchiolitis profiles were determined by latent class analysis, classifying children based on clinical factors and viral aetiology.

Results: In the US study, four profiles were identified. Profile A (12%) was characterised by history of wheezing and eczema, wheezing at the emergency department (ED) presentation and rhinovirus infection. Profile B (36%) included children with wheezing at the ED presentation, but, in contrast to profile A, most did not have history of wheezing or eczema; this profile had the largest probability of respiratory syncytial virus infection. Profile C (34%) was the most severely ill group, with longer hospital stay and moderate-to-severe retractions. Profile D (17%) had the least severe illness, including non-wheezing children with shorter length of stay. Two of these profiles (A and D) were replicated in the Finnish cohort; a third group ('BC') included Finnish children with characteristics of profiles B and/or C in the US population.

Conclusions: Several distinct clinical profiles (phenotypes) were identified by a clustering approach in two multicentre studies of children hospitalised for bronchiolitis. The observed heterogeneity has important implications for future research on the aetiology, management and long-term outcomes of bronchiolitis, such as future risk of childhood asthma.

Keywords: Paediatric Lung Disaese; Respiratory Infection; Viral infection.

Figure 1

Associations between profiles (A to D) identified by Latent Class Analysis (LCA) and treatment, in MARC-30 U.S. (n=2,207). Treatments: antibiotics, inhaled bronchodilators [bronch.], and systemic or inhaled corticosteroids [CS]) at emergency department (ED) presentation and during the inpatient stay. Results are presented as percentage of patients receiving treatment at ED presentation (% ED) and during the inpatient stay (%inpatient), and odds ratio (OR) and 95% confidence intervals (CI), adjusted for age, sex and race/ethnicity. Profile B was used as the reference category (% ED / % inpatient for antibiotics: 23 / 30; bronchodilators: 76 / 44; corticosteroids: 21 / 17). Profile A: history of wheezing/eczema, wheezing at ED presentation, more often rhinovirus. Profile B: wheezing at ED presentation, more often RSV only. Profile C: most severe. Profile D: non-wheezing at ED presentation, least severe.