The study evaluated the efficacy and safety of budesonide/formoterol in a single inhaler compared to placebo, budesonide, and formoterol in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). The 12-month, randomized, double-blind, placebo-controlled trial involved 812 adults with mean FEV1 of 36% predicted normal. Key outcomes included the number of severe exacerbations, FEV1, PEF, COPD symptoms, health-related quality of life (HRQL), mild exacerbations, and safety. Budesonide/formoterol significantly reduced the mean number of severe exacerbations per patient per year by 24% versus placebo and 23% versus formoterol. FEV1 increased by 15% versus placebo and 9% versus budesonide. Morning PEF improved significantly on day 1 versus placebo and budesonide, and this improvement was maintained over 12 months. Budesonide/formoterol also reduced symptom scores and the use of reliever β2-agonists, and improved HRQL. All treatments were well tolerated. The results suggest that budesonide/formoterol is an effective and safe treatment for long-term management of moderate-to-severe COPD.The study evaluated the efficacy and safety of budesonide/formoterol in a single inhaler compared to placebo, budesonide, and formoterol in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). The 12-month, randomized, double-blind, placebo-controlled trial involved 812 adults with mean FEV1 of 36% predicted normal. Key outcomes included the number of severe exacerbations, FEV1, PEF, COPD symptoms, health-related quality of life (HRQL), mild exacerbations, and safety. Budesonide/formoterol significantly reduced the mean number of severe exacerbations per patient per year by 24% versus placebo and 23% versus formoterol. FEV1 increased by 15% versus placebo and 9% versus budesonide. Morning PEF improved significantly on day 1 versus placebo and budesonide, and this improvement was maintained over 12 months. Budesonide/formoterol also reduced symptom scores and the use of reliever β2-agonists, and improved HRQL. All treatments were well tolerated. The results suggest that budesonide/formoterol is an effective and safe treatment for long-term management of moderate-to-severe COPD.