Patients with lower extremity peripheral arterial disease (PAD) are at increased risk for physical impairment and progressive functional decline. Structured exercise rehabilitation programs have been shown to significantly reduce the rate of functional decline in these patients. Because access to these programs is limited, it is important to find out if unsupervised exercise has comparable benefits. McDermott and colleagues conducted a prospective cohort study to assess the relationship between self-reported walking exercise and measures of functional status in men and women 55 years and older with symptomatic or asymptomatic PAD.
For the purpose of this study, PAD was defined as a calculated ankle-brachial index of less than 0.90 on noninvasive vascular testing. Participants were recruited from a consecutive sample of patients evaluated at three Chicago-area vascular laboratories between October 1998 and January 2000. Patients were excluded if they were wheelchair-bound, amputees, nursing home residents, or had dementia or recent major surgery. Also excluded were patients who underwent lower extremity revascularization before the first follow-up visit. Eligible patients were grouped by their reported activity level: (1) 107 patients who walked for exercise three or more times per week; (2) 118 patients who walked for exercise one or two times per week; and (3) 191 patients who did not walk for exercise. There were no statistically significant differences among the three groups in the prevalence of diabetes, cardiac disease, cerebrovascular disease, or arthritis.
Functional status measures were repeated annually over an average follow-up of36 months. Measures consisted of a timed six-minute walk; timed chair rises; 10-second standing balance; and “usual” and “fastest” 4-meter walking velocities. Performance in each of the latter three measures was assigned a score from 0 (unable to complete) to 4, based on performance quartiles from a previous epidemiologic study. These scores were combined into a summary performance score ranging from 0 to 12. Statistical analyses were performed to assess the association between activity level and degree of functional decline, controlling for variables such as age, sex, ethnicity, body mass index, education, leg symptoms, and cigarette use.
All of the groups experienced annual declines in walking distance and walking velocity, but functional declines were significantly smaller in patients who walked for exercise three or more times per week. These findings persisted when analyses were adjusted for the use of aspirin, angiotensin-converting enzyme inhibitors, and statins. Patients 65 years and older who walked for exercise were as likely to have reduced functional decline as younger patients.
The authors conclude that patients 55 years and older with asymptomatic or symptomatic PAD who walk for exercise at least three times per week experience significantly less functional decline than those who exercise less often. National surveys suggest that a minority of physicians routinely recommend aerobic exercise to their patients with PAD. Increased rates of counseling could benefit these patients. Because the observational design of this study cannot prove that walking preserves function, the authors suggest that a randomized controlled trial be performed to determine if the active promotion of walking exercise by physicians leads to better outcomes than usual care.