Nitric oxide is a naturally occurring gas that plays a role in many body functions. Levels of eNO increase with airway inflammation, a symptom of asthma. Researchers have proposed using eNO as a noninvasive measure to guide physicians in the treatment and medical management of asthma in children. However, more information about eNO is needed before this can happen. This study will perform a secondary analysis of the results from its parent study, the CAP study, which evaluated the effectiveness of preventing asthma in children who had been exposed to environmental tobacco smoke.~This study will not enroll any new participants. Previously collected data from the CAP study will be reevaluated in this study to determine the longitudinal effects of environmental and genetic factors on eNO levels. In addition, the data will be evaluated to determine the relationship between eNO levels and asthma severity. No new data will be collected in this study.
Asthma is one of the most common childhood diseases. It is chronic and often severely disabling. The amount of nitric oxide that is exhaled while breathing increases with airway inflammation, a symptom of asthma. This study will examine the results from a previous study, the Cincinnati Asthma Prevention (CAP) study, to evaluate the effects of environmental and genetic factors on exhaled nitric oxide (eNO) levels and to determine the relationship between eNO and asthma severity.