Epidemiology of asthma

Asthma is a disease characterized by bronchial hyperresponsiveness and ongoing airway inflammation and remodeling. Asthma prevalence has been steadily increasing over the past two decades. Recently, there has been a plateau in asthma prevalence rates in the United States. Asthma is a difficult disease to study epidemiologically secondary to the heterogeneity of the disease and the lack of a uniform means of diagnosis. Data collection by the NHIS relies on a personal history of wheezing or a diagnosis of asthma by a physician. The lack of a standardized definition and diagnostic tool makes it difficult to accumulate uniform epidemiologic data that can be used to determine the risk factors for asthma. The morbidity related to asthma is staggering. Persons afflicted with asthma miss more days at work or school than the average American. Asthma patients and their families spend on average $1000 per year on medications. The annual cost of asthma in 1998 was estimated to be $11.3 billion with hospitalizations accounting for most of these costs. The costs associated with asthma continue to increase. The asthma mortality rate has recently decreased, which may be related to overall decrease in prevalence and advances in diagnosis and pharmacologic management of asthma. The ethnic differences in asthma mortality rates are staggering. Non-Hispanic black persons have the highest mortality rates, which are 200% higher than death rates in non-Hispanic whites. African American men between the ages 25 and 35 years old are at the greatest risk of dying asthma. Studies have shown that lack of access care, tobacco use, environmental exposures particularly in inner city areas, poor asthma control, and genetic influences on response to medication contribute to the current situation. Physicians have large role to play in decreasing the mortality rates associated with asthma. Physicians continue underprescribe inhaled corticosteroids despite preponderance of evidence from clinical trials showing significant mortality benefits. Most patients undereducated about their disease and do not know how to use a peak flow meter. Physicians do not discuss or establish asthma action plans with their patients and underuse tools that help patients achieve better control of their disease. There are disparities health care provided to patients despite their ability pay for medical care. These disparities in health care delivery need to be addressed if the goal of decreased asthma death is to be achieved. Asthma is an area of active research with ongoing investigation of the epidemiology, genetics, and interaction of environment and susceptibility in development of asthma. The physiologic occurrence of inflammation and airway remodeling is a fascinating new area of research in asthma, which may lead to the development of novel new therapies. Many complex mechanisms contribute to the underlying disease and its natural history. The global burden asthma is significant and continued investigation into new mechanisms of asthma and the application current knowledge will result in decreased morbidity and mortality in the future.