Birth Cohorts in Childhood Asthma: Lessons and Limitations

The role of rhinovirus infection as a major trigger of asthma exacerbations in the preteens was recognized over 15 years ago, when molecular diagnostic methods were first used to study children with asthma in a community setting (1). A viral precipitant was identified in 80% of asthma exacerbations in this age group, and rhinovirus was the most common culprit. The Childhood Origins of Asthma (COAST) study, an important birth cohort inaugurated over a decade ago, has investigated the role of rhinovirus at an earlier age. Results from this cohort, published in 2008, suggested that rhinovirus might also have a role in the etiology of asthma in young children at high risk of asthma and allergic disease (2). More than 90% of children with wheezing episodes associated with rhinovirus infection at the age of 3 years in this cohort would go on to have protocol-defined asthma at age 6 years. The risk of later asthma with rhinovirus wheeze was greater than that seen with respiratory syncytial virus (RSV). Furthermore, rhinovirus wheezing episodes appeared to be a more important risk factor than allergic sensitization. A further report from the COAST study, in this issue of the