Asthma exacerbations: origin, effect, and prevention

Abstract

Asthma is the most common chronic respiratory disease, affecting up to 10% of adults and 30% of children in the Western world. Despite advances in asthma management, acute exacerbations continue to occur and impose considerable morbidity on patients and constitute a major burden on health care resources. Respiratory tract viruses have emerged as the most frequent triggers for exacerbations in both children and adults; however, the mechanisms underlying these remain poorly understood. More recently, it has become increasingly clear that interactions might exist between viruses and other triggers, increasing the likelihood of an exacerbation. In this article we begin with an overview of the health, economic, and social burden that exacerbations of asthma carry with them. This is followed by a review of the pathogenesis of asthma exacerbations, highlighting the various triggers responsible and multiple interactions that exist between them. The final section first addresses what preventative measures are currently available for asthma exacerbations and subsequently examines which of the new treatments in development might lessen the burden of exacerbations in the future.

Fig 1

The annual cycle of asthma hospitalization in children aged 2 to 15 years in Canada from 1990 to 2004 expressed as multiples of the within-year weekly mean number of hospitalizations showing epidemic peak occurring in September every year.

Fig 2

Kaplan-Meier estimates of cumulative risk of hospital admission with wheeze or asthma during the first 8 years of life stratified on 5-class model. A, Age at first hospital admission for children who had a hospital admission with wheeze or asthma at any age. B, Age at first hospital admission among children who had a hospital admission after age 3 years. A significant increase in the risk of hospital admission with acute asthma is seen only among children in the multiple early class, but not among those in any of the other atopy classes.