Phenotypes of recurrent wheezing in preschool children:
Identification by latent class analysis and utility in
prediction of future exacerbation

BACKGROUND: Recurrent preschool wheezing is a heterogeneous disorder with significant morbidity, yet little is known about phenotypic determinants and their impact on clinical outcomes. OBJECTIVE: Latent class analysis (LCA) was used to identify latent classes of recurrent preschool wheeze and their association with future exacerbations and inhaled corticosteroid (ICS) treatment response. METHODS: Data from 5 clinical trials of 1708 children aged 12 to 71 months with recurrent wheezing were merged. LCA was performed on 10 demographic, exposure, and sensitization variables to determine the optimal number of latent classes. The primary outcome was the annualized rate of wheezing exacerbations requiring systemic corticosteroids during the study intervention period; the secondary outcome was the time to first exacerbation. Exploratory analyses examined the effect of daily ICS treatment on exacerbation outcomes. RESULTS: Four latent classes of recurrent wheezing were identified; these were not distinguished by current symptoms or historical exacerbations but differed with regard to allergen sensitization and/or exposures. Annualized exacerbation rates (mean $\pm$ SEM/year) were 0.65 $\pm$ 0.06 for class 1 (``minimal sensitization''), 0.93 $\pm$ 0.10 for class 2 (``sensitization with indoor pet exposure''), 0.60 $\pm$ 0.07 for class 3 (``sensitization with tobacco smoke exposure''), and 0.81 $\pm$ 0.10 for class 4 (``multiple sensitization and eczema'') (P < .001). In a research setting of high adherence, daily ICS treatment improved exacerbation rates in classes 2 and 4 but not the other groups. CONCLUSIONS: Sensitization and exposure assessments are useful in the prediction of future exacerbation and may identify children most likely to respond favorably to daily ICS treatment.