OBJECTIVES: This was a prospective, randomized, multicenter, open label study to determine the cost-effectiveness (CE) of levalbuterol versus racemic albuterol in patients hospitalized for acute asthma or COPD; here we present a subset CE analysis which focuses on quality-adjusted length of stay (QLOS) as a measure of effectiveness. METHODS: Patients were randomized to either levalbuterol (n=241) or racemic albuterol (n=238). We conducted an exploratory CE analysis using QLOS, which was developed to reflect the relative rapidity of symptom resolution over the patient's hospital stay, conceptually similar to Q-TWiST. A measure of overall HRQoL based on daily responses to the Subject General Well-Being (SGWB) score was used as the utility value. An overall value was obtained by calculating the sum over the time period, resulting in the QLOS score. QLOS was also calculated for two other effectiveness measures, Disease Symptom Assessment (DSA) and beta-mediated treatment effects (BMTE). Hospital charges obtained from billing records were converted to costs by applying cost-to-charge ratios. A cost/QLOS comparison was made between treatment groups. Sensitivity analyses examined different time periods and measures of effectiveness. Bootstrap sampling was used to generate 10,000 samples for each analysis. RESULTS: When SGWB was the effectiveness measure, levalbuterol compared to racemic albuterol was associated with lower costs ($3,676 vs. $3,841, respectively) and slightly better cumulative effectiveness (11.99 vs. 12.68, respectively; lower value better health). Similar results were observed using other time periods and BMTE as the effectiveness measure. Results from bootstrap sampling showed that, in the majority of samples, levalbuterol was associated with better health and lower costs than racemic albuterol. When DSA was used, racemic albuterol was slightly more effective but more costly than levalbuterol. CONCLUSION: In this study using prospectively collected cost data and QLOS scores, levalbuterol was at least as effective as racemic albuterol, with total costs that were $165 less.