Ann Intern Med -- Aaron et al. 146 (8): 545 Figure 2

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Figure 2. Kaplan–Meier estimates of the probability of remaining free of exacerbations, according to treatment assignment.

The unadjusted hazard ratio was 1.02 (95% CI, 0.77 to 1.37) for tiotropium plus placebo versus tiotropium plus salmeterol (P = 0.87) and 0.80 (CI, 0.60 to 1.08) for tiotropium plus placebo versus tiotropium plus fluticasone–salmeterol (P = 0.15). COPD = chronic obstructive pulmonary disease.