Methods of Determining Asthma Severity in Children

Overview

Current methods of measuring asthma severity can be problematic when used with children. A measurement called exhaled breath condensates (EBC) may be a more useful way to determine asthma severity in childhood. The purpose of this study is to determine if EBC measurements are useful for determining asthma severity in asthmatic children as compared to currently used laboratory measures. Study hypotheses: 1) A broad panel of EBC measures will distinguish asthmatic children not on inhaled corticosteroids (ICS) from both asthmatic children routinely taking ICS and nonasthmatic controls. 2) Standardized equipment and methodologies for EBC collection, processing, storage, shipping, and pH and mediator measurements can be developed that will eliminate significant contamination from oropharyngeal saliva and allow for shipping and processing at a central site.

The current national guidelines for assessing asthma severity have several limitations for use in asthmatic children. One major limitation is that spirometric measures of airflow limitation, including forced expiratory volume in one second (FEV1), generally cannot be reliably obtained in children less than 7 years of age. Furthermore, most children with asthma have essentially normal measures of airflow by spirometry or peak flow, so such measurements are generally not useful in diagnosis and treatment. Previous studies indicate that lung-specific biomarkers of inflammation, such as bronchial hyperresponsiveness measures, might simplify, improve, and optimize the guidelines. Collection of EBC samples may also be useful; EBC samples can be obtained by noninvasive means and are easier to obtain than conventional samples. However, contamination by saliva is an issue in collecting EBC samples, and standardization of sample collection is needed. This study will compare the utility of two different sample collecting equipment, the EcoScreen and the R-Tube. This study will also evaluate the usefulness of EBC samples in distinguishing between asthmatic children taking ICS, asthmatic children not taking ICS, and nonasthmatic children. There are 2 parts to this study. In Part A, two EBC samples will be collected from each participant. Some participants will be have one EBC sample taken by the EcoScreen and the other taken by the R-Tube; other participants will have both samples taken by the R-Tube. In Part B, asthmatics taking ICS, asthmatics not taking ICS, and nonasthmatics will give 2 EBC samples each via the R-Tube. Participants will be asked to complete a questionnaire on their asthma symptoms and allergies and will have a brief physical exam. Allergy skin prick testing, urine collection, measurement of exhaled nitric oxide, and conventional incentive spirometry (used to obtain several measures of lung function) will also occur. Participants will also be asked to donate a blood sample.