BACKGROUND:

Asthma is a chronic inflammatory disease. T lymphocytes are essential for initiating and maintaining the asthmatic inflammatory immune response. Corticosteroid treatment targets several inflammatory responses, including T lymphocytemediated responses. In addition, leukotriene receptor antagonists (LTRA) may influence T cell activation. To investigate the effects of these two controller agents in the treatment of asthma on airway function is the goal of the IMPACT clinical trial in mild chronic adult asthmatics. The Improving Asthma Control Trial (IMPACT) is one of the trials within the NHLBI-supported Asthma Clinical Research Network (ACRN). IMPACT is a double-blind, randomized, parallel group design clinical trial to determine the best long-term strategy for treating adults with mild asthma who experience symptoms more than occasionally. The trial will test whether these patients should be taking anti-inflammatory medications on a daily basis and whether a newer class of medications provides the same benefit as older drugs. In the IMPACT study, 234 adults with mild asthma who have more than occasional symptoms will be enrolled in six clinical research centers. Following an initial evaluation, patients will be randomized to receive either a twice daily inhaled corticosteroid, a twice daily anti-leukotriene, or a placebo. All patients will receive treatment for symptoms if and when they occur. The results should demonstrate whether medication is required on a daily basis by these patients, and if so, whether inhaled corticosteroids and leukotriene modifiers are equally effective. Recruitment began in May, 2000. The trial is expected to be completed in 2003.

The study is in response to an initiative "Ancillary Studies in Heart, Lung, and Blood Disease Trials" released by the National Heart, Lung, and Blood Institute in June 2000.

DESIGN NARRATIVE:

A total of 39 patients, 13 in each arm, will be randomized to inhaled steroid, leukotriene receptor antagonist or placebo and followed for 18 months for changes in T-cell costimulatory pathways.