Asthma and COPD are among the leading causes of illness in children and adults, respectively. Asthma is the most common long-term disease among children in the developed world, and approximately 16 million people in the United States have COPD, which is now the fourth most common cause of death in this country. Vitamin D, both a nutrient and a hormone, can be taken in through diet and exposure to sunlight. Many children and adults have a vitamin D deficiency and there is concern that current recommended intake levels may be inadequate. A vitamin D deficiency can cause immune system dysfunction and may increase the risk of developing immune-mediated disorders, such as multiple sclerosis, inflammatory bowel disease, rheumatoid arthritis, and various cancers. Because of its role in immune development and function, a vitamin D deficiency may also be related to the development of severe asthma in children and to greater lung function decline in adults, leading to COPD. Preliminary research shows that people with asthma who take vitamin D have an enhanced response to corticosteroids, a common medication used to treat asthma. This finding suggests that vitamin D could possibly be used to improve asthma treatment. The purpose of this study is to measure vitamin D levels in participants of three previous studies and determine whether lower vitamin D levels are related to the development of severe asthma or COPD.
This study will examine previously collected blood samples from participants in three studies. There will be no study visits specifically for this study. The three studies include the following:
* Childhood Asthma Management Program, which is a study that examined the use of inhaled corticosteroids, nedocromil, and placebo in children with mild-to-moderate asthma
* Genetic Epidemiology of Asthma in Costa Rica, which is an ongoing study that is identifying genetic predictors of asthma in Costa Rican families with asthma
* Normative Aging Study, which is a study of aging that is being conducted in men living in Boston
