Toward a definition of asthma phenotypes in childhood: Making a long way shorter?

Abstract

Asthma is a global health problem that imposes a burden on the family, the health care system, and society as a whole and results in massive social and economic costs to the community. In most cases asthma has its origins in early childhood, when the interaction of genetic and environmental factors shape airways development in a healthy or pathologic direction. Many attempts have been made to stop asthma in its early stages in childhood. Unfortunately, long-term pharmacologic treatment, allergen avoidance, or other strategies can hardly modify the natural course of the disease. Guidelines have been based on a uniform therapeutic approach, as if asthma were rather homogeneous. However, early childhood asthma has highly heterogeneous phenotypes, and a mismatch between heterogeneous phenotypes and homogeneous therapy contributes to treatment failure. For a few years, it has been debated whether asthma should be seen as a single disease or rather a ‘‘syndrome’’ including multiple, separate, and overlapping ‘‘asthma-like’’ mild and severe diseases differing in risk factors, triggers, mechanisms, pathophysiology, and natural course and therefore requiring tailored diagnostic and therapeutic approaches. Hence not only standard diagnostic or therapeutic approaches but also standard predictive and preventive strategies can be nonspecific in most patients because the strategies do not suit the wide heterogeneity of asthma phenotypes. Therefore it is essential that we learn to identify in early life the different asthma phenotypes and their risk factors, profiles, and pathophysiologic mechanisms. In this issue of the Journal, Just et al use cluster analysis for 551 wheezing 3-year-old infants to characterize the heterogeneity of wheeze in early childhood. On the basis of 19 variables, they describe 3 independent groups of wheezing children: early viral wheezers, multitrigger wheezers (MTWs), and nonatopic uncontrolled wheezers (NAUWs). The first category might correspond to the ‘‘early wheezers’’ described almost 2 decades ago by Martinez et al. The remaining 2 clusters describe infants with more severe wheezing and quite polarized characteristics: MTW