Figure 3.

Exercise capacity results from the National Emphysema Treatment Trial. Improvement in exercise capacity (defined as an increase in maximum work of 10 watts above the patient's post–rehabilitation baseline) at 1, 2, and 3 years after randomization to lung volume reduction surgery (LVRS) (open bars) or medical treatment (shaded bars). Intention to treat analysis of (A) all patients (n = 1,218) and (B) upper lobe–predominant and low baseline exercise capacity (n = 290). Shown below each graph are the numbers of patients evaluated, the odds ratio for improvement (LVRS:medical), and the Fisher's exact P value for difference in proportion improved. Patients who died or who did not complete the assessment were considered not improved (3).