OBJECTIVES: Randomized clinical trials (RCTs) are the gold standard for determining efficacy of pharmaceutical treatments, but findings from RCTs are often difficult to translate into real-world (non-randomized) environments. This observational registry was designed to identify real-world outcomes among asthma patients receiving various treatments for asthma. The registry protocol mirrored a previous RCT and was designed to provide confirmatory evidence for generalizability of prior research findings. METHODS: Four hundred eighty-four physicians from 13 states, including the west, central, northeastern, southeastern and midwestern areas of the U.S., were recruited and trained in registry procedures. Patients were eligible if they were 15 years or older and required a change in asthma control therapy as determined by their physician during a regularly scheduled office visit. No recruitment was allowed to protect the observational status of the registry. Asthma Control Questionnaire (ACQ), Asthma Quality of Life Questionnaire (AQLQ), medication satisfaction, and productivity end point data have been obtained from baseline and will be obtained from 1-month, 3-month, 6-month and 1-year surveys. Utilization and cost data for inpatient, outpatient, emergency room, and prescriptions will be obtained from the individual's health insurance claims data. RESULTS: Eighty-one percent of physicians were general internists, and 19% were allergists or pulmonologists. Sixty-seven percent of all physicians had no previous research experience. Over 1400 patients entered the registry during the enrollment period (01/2002-12/2002). Baseline characteristics were well balanced across the four cohorts despite lack of randomization. Analysis of baseline self-reported ACQ and AQLQ individual questions identified no statistically significant differences between cohorts. Follow-up survey results will be reported in future analyses. CONCLUSIONS: Non randomized registry studies can complement RCTs by providing an ample well balanced sample size that is representative of real-word practice and makes available rapid feedback on clinical and economic outcomes.