Asthma is a chronic condition associated with significant health and economic burden to patients, families, and society. Its symptoms of cough, wheeze, shortness of breath, and chest tightness are associated with variable airflow limitation that is at least partly reversible. Asthma is estimated by the World Health Organization to affect 150 million people worldwide, and its global pharmacotherapeutic costs exceed $5 billion per year. Although patients suffering from asthma share similar clinical symptoms, the disease itself is heterogeneous in terms of phenotypes and natural history. This heterogeneity is compounded by combinations of environmental exposures that occur in utero, in early life, and across the life span, which contribute to the difficulty in both studying and treating asthma. This challenge is especially evident in children, for whom asthma remains the leading cause of emergency care and hospitalization rates continue to rise.
Currently, there are no national measures of the incidence of asthma and the rate at which it develops over time. However, the prevalence of asthma has been tracked by the National Health Interview Survey (NHIS), which is used to produce annual health estimates based on self-report of a nationally representative sample. Prevalence identifies the population in need of effective measures to control asthma symptoms. Between 1980 and 1995, the prevalence of asthma among children 0 to 17 years of age more than doubled, from 3.6% in 1980 to 7.5% at the peak of the trend in 1995. Although the prevalence rate has leveled off since then, prevalence remains high, and in 2005, 12.7% of children had been diagnosed with asthma at some point in their lifetime (9 million children), of whom 70% were reported to currently have asthma (6.5 million). Although some countries have seen a decline in asthma-related hospitalizations and deaths, the global burden for patients from exacerbations and day-to-day symptoms has increased by almost 30% in the past 20 years. Nearly two-thirds of these children who currently have asthma reported at least 1 attack in the previous 12 months. Ambulatory care use for asthma has continued to grow since 2000, while the overall rate of ambulatory care use for children has not increased. Despite increased overall healthcare utilization and the fact that there are means to prevent attacks or exacerbations among children with asthma, the majority of children with asthma still suffer from attacks. Furthermore, the burden of avoidable emergency department visits and hospitalizations for asthma is high and has remained resistant to intervention. It is estimated that at least 70% of all children who have asthma have persistent asthma.
In a recent systematic review, all existing childhood asthma prediction models were assessed for their potential to identify preschool children who will develop asthma at school age. Twelve prediction models were identified, and no single model was able to predict asthma development.
Racial disparities in childhood asthma are extensive. Children of American Indian or ...