Longitudinal Observational Study of Severe Asthma

Background: \- Asthma is a lung condition that causes difficulty breathing and decreased lung function. Some people with asthma have more severe disease symptoms. They may be less responsive to standard treatments such as steroids. Researchers want to compare severe asthmatics with mild or moderate asthmatics or people without asthma over a long period. This information may help identify new treatments for people whose asthma is not well controlled by standard medications. Objectives: \- To compare severe asthmatics with mild or moderate asthmatics, and healthy volunteers, to study the progression and outcomes of the disease. Eligibility: * Individuals at least 18 years of age who have been diagnosed with asthma for at least 1 year. * Healthy volunteers at least 18 years of age. Design: * This study will involve an initial visit to the NIH Clinical Center for all participants. Selected participants may be asked to return for repeat visits over a number of years. The test results from participants with asthma will be compared with those from the healthy volunteers. * All participants will be screened with a physical exam and medical history. * Participants may (but will not necessarily) have the following tests at each visit: * Complete medical history and physical exam * Blood, urine, sputum, and nasal cell samples * Breath tests and heart and lung function tests * Six-minute walk test to measure ability to exercise * Imaging studies such as chest x-rays, bone density scans, and sinus scans * Allergy skin testing * Vocal cord exam * Overnight sleep study * Participants may remain on the study for as long as they are willing to participate and do not develop health problems that will interfere with the study.

Asthma is a common disease and a significant public health problem, affecting one in every 10 individuals, nearly 30 million people in the US alone. About 5-10% of asthmatics have severe disease that is difficult to control with standard therapies. Severe asthmatics are considered to be relatively resistant to corticosteroids, a mainstay of therapy in asthma. Furthermore, chronic corticosteroid therapy often results in side effects that adversely affect outcomes. Thus, more effective treatment options, which are safe, cost-effective and easy to administer, are needed for severe asthmatics. As our understanding of asthma evolves, it is becoming clearer that there are distinct phenotypes that differ regarding demographic factors such as age, sex and race, but also, perhaps more importantly, with regards to clinical, physiologic and biologic characteristics. This heterogeneity may reflect distinct pathogenic mechanisms that result in airflow obstruction and the clinical presentation of asthma. In turn, a better understanding of the different factors that contribute to disease severity and pathogenesis will be necessary to identify new, personalized treatment and management approaches for severe asthmatics. Our goal is to gain a better understanding of the pathogenic mechanisms that differentiate severe asthma from mild to moderate asthma, including the role of the above-mentioned factors on disease control. In so doing, we hope to discover novel pathways that can be manipulated to achieve our primary aim of developing new therapies for severe asthmatics.