BACKGROUND: Clinical studies have demonstrated the efficacy and relative safety of inhaled corticosteroids in the treatment of asthma. However, effectiveness and cost-effectiveness comparisons of available inhaled corticosteroids in real-life clinical settings are lacking. OBJECTIVE: This study compared the effectiveness and safety of budesonide administered via dry-powder inhaler versus that of triamcinolone acetonide administered via pressurized metered-dose inhaler in the treatment of adult patients with persistent asthma treated in a managed care setting. METHODS: This was a randomized, open-labe, 52-week study of adult patients (aged >or= 18 years) with persistent asthma enrolled in 25 US health plans. The primary study outcome was mean change from baseline to the end of treatment in symptom-free days. Secondary variables were changes from baseline in number of episode-free days, episode-free days at 52 weeks, forced expiratory volume in 1 second (FEV(1)), forced vital capacity, asthma symptom scores, breakthrough bronchdilator use, patient discontinuations, and health-related quality of life. Patients were issued diaries in which to record use of study medication and concomitant asthma medication use, as well as daytime and nighttime asthma symptom severity. Patients were assessed at weeks 4, 13, 26, 39, and 52. Safety was assessed based on adverse events and changes in laboratory tests, vital signs, and physical examinations. RESULTS: A total of 945 patients (344 men, 601 women; mean [SD] age, 46.8 [14] years) were enrolled; 631 received budesonide and 314 received triacinolane acetonide. Improvements in all effectiveness variables were observed with both treatments. The mean increase from baseline in the number of symptom-free days per month assessed at month 12 was 7.74 (95% CI, 6.81-8.66) for patients receiving budesonide and 3.78 (95% CI, 2.47-5.09) for patients receiving triamcinoline acetonide ( P<0.001). The estimated annual mean (SD) number symptom-free days for patients receiving budesonide was 141.1 (125.0) over the treatment phase, compared with 99.3 (112.1) for those receiving triamcinolone acetonide (P<0.001). Patients receiving budesonide demonstrated significant improvements (compared with those receiving triamcinolone acetonide) in overall quality of life, daytime and nighttime asthma symptom severity, breakthrough bronchodilator use, and FEV(1) (all P<0.001). Safety measures were similar between groups. CONCLUSION: In these managed care settings, budesonide inhalation powder administered via dry-powder inhaler was significantly more effective than triamcinolone acetonide administered via pressurized metered-dose inhaler in the treatment of adults with persistent asthma.