Six-minute walking distance did not improve after 12 months of low-intensity home-based walking exercise in a recent study of patients with peripheral artery disease (PAD).
Researchers performed a multicenter randomized controlled trial to determine whether low-intensity walking exercise at home improved walking ability in patients with PAD compared with high-intensity, ischemia-inducing home-based walking exercise and with a nonexercise control group. Patients in both exercise groups were asked to walk for exercise for up to 50 minutes per session five times per week while wearing an accelerometer to document time and intensity. Exercise was not supervised. Those in the low-intensity group walked at a pace that did not induce ischemic leg symptoms, while those in the high-intensity group walked at a pace that caused moderate to severe symptoms.
A coach viewed the accelerometer data from the exercise groups and called patients on a weekly basis for 12 months to help with exercise adherence. Those in the nonexercise group received educational phone calls weekly for 12 months. The study's primary outcome was mean change in 6-minute walk distance at 12 months, with 8 to 20 m defined as the minimum clinically important difference. Results were published April 6 by JAMA.
Three hundred five patients participated in the study, 116 in the low-intensity group, 124 in the high-intensity group, and 65 in the control group. Enrollment occurred between Sept. 25, 2015, and Dec. 11, 2019, with Oct. 7, 2020, as final follow-up. Mean age was 69.3 years, 47.9% of patients were women, and 59.3% were Black. Two hundred fifty patients (82%) completed the 12-month follow-up. In the low-intensity group versus the high-intensity group, 6-minute walk distance changed from 332.1 m at baseline to 327.5 m at 12-month follow-up (within-group mean change, −6.4 m [95% CI, −21.5 to 8.8 m]; P=0.34) versus from 338.1 m to 371.2 m (within-group mean change, 34.5 m [95% CI, 20.1 to 48.9 m]; P<0.001). Mean change for the between-group comparison was −40.9 m (97.5% CI, −61.7 to −20.0 m; P<0.001). In the nonexercise control group, 6-minute walk distance changed from 328.1 m at baseline to 317.5 m at 12-month follow-up (within-group mean change, −15.1 m [95% CI, −35.8 to 5.7 m]; P=0.10), which was not significantly different from the change in the low-intensity exercise group.
The low-intensity group did see improvement versus the nonexercise control group in the secondary outcomes of distance and speed scores on the Walking Impairment Questionnaire at six and 12 months. One hundred eighty-four serious adverse events occurred during the study, with one serious adverse event in each exercise group related to participation in the study. Rates of serious adverse events per participant were 0.64 in the low-intensity group, 0.65 in the high-intensity group, and 0.46 in the nonexercise control group.
Among other limitations, the researchers noted that 18% of patients did not return for 12-month follow-up and that planned treadmill stress tests could not be conducted after March 2020 due to the COVID-19 pandemic, resulting in missing data. They concluded that low-intensity home-based exercise was significantly less effective than high-intensity home-based exercise in patients with PAD and did not differ significantly from no exercise in improving 6-minute walk distance. “These results do not support the use of low-intensity home-based walking exercise for improving objectively measured walking performance in patients with PAD,” the authors wrote.