Effect of Granulocyte-Macrophage Colony-Stimulating Factor With or Without Supervised Exercise on Walking Performance in Patients With Peripheral Artery Disease The PROPEL Randomized Clinical Trial

IMPORTANCE Benefits of granulocyte-macrophage colony-stimulating factor(GM-CSF) for improving walking ability in people with lower extremity peripheral artery disease (PAD) are unclear. Walking exercise may augment the effects of GM-CSF in PAD, since exercise-induced ischemia enhances progenitor cell release and may promote progenitor cell homing to ischemic calf muscle. OBJECTIVES To determine whether GM-CSF combined with supervised treadmill exercise improves 6-minute walk distance, compared with exercise alone and compared with GM-CSF alone; to determine whether GM-CSF alone improves 6-minute walk more than placebo and whether exercise improves 6-minute walk more than an attention control intervention. DESIGN, SETTING, AND PARTICIPANTS Randomized clinical trial with 2 x 2 factorial design. Participants were identified from the Chicago metropolitan area and randomized between January 6, 2012, and December 22, 2016, to 1 of 4 groups: supervised exercise + GM-CSF (exercise + GM-CSF) (n = 53), supervised exercise + placebo (exercise alone) (n = 53), attention control + GM-CSF (GM-CSF alone) (n = 53), attention control + placebo (n = 51). The final follow-up visit was on August 15, 2017. INTERVENTIONS Supervised exercise consisted of treadmill exercise 3 times weekly for 6 months. The attention control consisted of weekly educational lectures by clinicians for 6 months. GM-CSF (250 mu g/m(2)/d) or placebo were administered subcutaneously (double-blinded) 3 times/wk for the first 2 weeks of the intervention. MAIN OUTCOMES AND MEASURES The primary outcome was change in 6-minute walk distance at 12-week follow-up (minimum clinically important difference, 20 m). P values were adjusted based on the Hochberg step-up method. RESULTS Of 827 persons evaluated, 210 participants with PAD were randomized (mean age, 67.0 [SD, 8.6] years; 141 [67%] black, 82 [39%] women). One hundred ninety-five (93%) completed 12-week follow-up. At 12-week follow-up, exercise + GM-CSF did not significantly improve 6-minute walk distance more than exercise alone (mean difference, -6.3m[95% CI, -30.2 to + 17.6]; P =.61) or more than GM-CSF alone (mean difference, + 28.7m[95% CI, + 5.1 to + 52.3]; Hochberg-adjusted P =.052). GM-CSF alone did not improve 6-minutewalk more than attention control + placebo (mean difference, -1.4m[95% CI, -25.2 to + 22.4]; P =.91). Exercise alone improved 6-minutewalk compared with attention control + placebo (mean difference, + 33.6m [95% CI, + 9.4 to + 57.7]; Hochberg-adjusted P =.02). CONCLUSIONS AND RELEVANCE Among patients with PAD, supervised treadmill exercise significantly improved 6-minute walk distance compared with attention control + placebo, whereas GM-CSF did not significantly improve walking performance, either when used alone or when combined with supervised treadmill exercise. These results confirm the benefits of exercise but do not support using GM-CSF to treat walking impairment in patients with PAD.