Preliminary pharmacoeconomic analyses suggest that levalbuterol (LEV) therapy is associated with decreased outpatient asthma healthcare costs. OBJECTIVE: Examine treatment costs in asthma patients stratified by the number of prescribed controller medications (CM), an index of asthma severity. METHODS: Claims data on patients prescribed LEV and RAC were obtained from the PharMetrics Integrated Outcomes Database. Age- and sex-matched samples of patients initiating therapy with LEV or RAC (no prescriptions for either agent in prior 6 months) were selected and their asthma-related charges were assessed over 6 months following the initial prescription. RESULTS: 544 LEV-treated patients were identified and matched to 544 RAC-treated patients. 62% of RAC patients previously received no CM, 20% had 1 CM, and 18% had >1 CM. Following RAC treatment 30% had 1 CM and 29% had >1 CM. Use of leukotriene modifiers increased from 8% to 14% and corticosteroid use increased from 33% to 46%. Although LEV patients previously received more CM (41% no CM; 24% 1 CM; 34% >1 CM), after treatment the percent with >1 CM declined to 28%. Their leukotriene modifier use increased from 22% to 25% while long-acting bronchodilator use decreased from 13% to 10%. In patients without prior CM, mean charges declined by similar amounts in both groups (LEV: $360, RAC: $306) following treatment. In patients with 1 CM, LEV was associated with a $116 reduction despite a $121 increase in pharmacy charges while RAC was associated with a $22 decrease. In patients with >1 CM, LEV was associated with a $435 reduction in mean charges while RAC was associated with a $311 increase. CONCLUSIONS: Asthmatic patients treated with LEV required no additional CM and some patients reduced the number of CM. Cost reductions associated with LEV increased with severity.