Four-year trial of tiotropium in chronic obstructive pulmonary disease

Tashkin DP, Celli B, Senn S, Burkhart D, Kesten S, Menjoge S, et al. A 4-year trial of tiotropium in chronic obstructive pulmonary disease. N Engl J Med 2008;359(15):1543–54. Epub 2008 Oct 5. Does long-term treatment with tiotropium alter the rate of decline in forced expiratory volume in 1