Asthma phenotypes in low income children: A cluster analysis

Abstract

Background: Asthma studies characterizing phenotypes have included predominately adults or been performed in children from developed countries. However, this applicability to other population such as in-developing countries remains undetermined. Objective: The purpose of this study is to determine how low-income Brazilian asthmatic children are distributed across a cluster analysis. Methods: This observational study included 306 asthmatic children and adolescents, both genders, aged 7 to 18 years old, with a clinical diagnosis of asthma according to GINA, under medical treatment for at least one-year of follow-up were included. Twenty variables commonly measured in clinical practice and considered important in defining the disease phenotype were selected for cluster analysis and those variables with high multicollinearity were not included. A cluster analysis was applied using an agglomerative two-step test and the log-likelihood method distance measure. Results: 3 clusters were defined in our population. In cluster 1 (n=94 patients), children had normal pulmonary function, low eosinophil inflammation, low exacerbation, late-onset asthma and low atopy status; in cluster 2 (n=87 patients), children had normal pulmonary function, high eosinophil inflammation and atopy status, moderate exacerbation and early-onset of asthma; in cluster 3 (n=108), children had poor pulmonary function, high eosinophil inflammation and atopy status and high exacerbation. Conclusion: Childhood asthma in low income Brazilian children is characterized by the presence of atopy, a high rate of exacerbation and fairly preserved lung function. Many similarities with the previous clusters indicate that this approach has good generalizability.