%0 Journal Article %A Orianne Dumas %A Jonathan M Mansbach %A Tuomas Jartti %A Kohei Hasegawa %A Ashley F Sullivan %A Pedro A Piedra %A Carlos A Camargo, Jr %T A clustering approach to identify severe bronchiolitis profiles in children %D 2016 %R 10.1136/thoraxjnl-2016-208535 %J Thorax %P 712-718 %V 71 %N 8 %X 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. %U https://thorax.bmj.com/content/thoraxjnl/71/8/712.full.pdf