A 65-year-old man with chronic obstructive pulmonary disease presents for routine review. He has chronic cough and sputum production and is short of breath walking one block. He has had two moderate exacerbations in the past year requiring oral steroids but no hospitalizations. Post-bronchodilator spirometry shows FEV1/FVC ratio 0.55 and FEV1 45% predicted. He is currently using only a short-acting beta-agonist as needed. According to current COPD strategy, which initial maintenance pharmacologic regimen is most appropriate?