Lack of relationship between gait parameters and physical function in peripheral arterial disease.

OBJECTIVE: Physical function is limited in patients with peripheral arterial disease who are symptomatic with intermittent claudication (PAD-IC). When patients with PAD-IC experience claudication, previous reports have described gait abnormalities, including alterations in step length and cadence. This study tested the hypothesis that patients with PAD-IC would have a decrease in usual and maximal walking speed and that this alteration in gait parameters would contribute to their decreased physical function scores, even in the absence of claudication. The aims were to evaluate usual and maximal walking speed and gait parameters (step length, cadence and toe out angle) in subjects with PAD-IC and control subjects with similar baseline activity levels.
METHOD: A cross-sectional study of 25 subjects with PAD-IC compared with 26 age-matched controls was conducted in a research laboratory in an academic medical center. Study subjects were similar in age, gender, and physical activity status. Subjects with PAD-IC had an ankle-brachial index <0.90 in at least one leg and reported symptoms of intermittent claudication that limited walking ability. Subjects in either group were excluded if they used assistive devices to walk or were limited in walking ability by orthopedic, neurologic, cardiac, or pulmonary symptoms. Gait parameters were assessed at the onset of walking (before the development of claudication pain in the PAD-IC group) at self-selected and maximal walking speeds during which step and stride characteristics were collected. Subjects completed a physical activity recall, a Short Form questionnaire (SF-36), and a 6-minute walk that was limited by claudication in the PAD-IC group.
RESULTS: During gait testing, no patient with PAD-IC developed claudication. There were no significant differences between the PAD-IC and control groups in usual or maximal walking speed or other gait variables (step length, cadence, stride width, toe out angle). In contrast, the SF-36 physical function score was reduced 15.2 percentage points (P < .02) and the summary physical component score was reduced 6.7 percentage points in the PAD-IC group compared with controls (P = .002). In addition, the 6-minute walk distance was significantly less in the PAD-IC group than in the control group by 308.8 feet (P < .001). A series of bivariate analyses demonstrated that PAD-IC was the best predictor of reduced physical function, whereas no gait parameter was associated with reduced physical function.
CONCLUSION: Patients with PAD-IC have significantly reduced 6-minute walk distance and reduced physical function by questionnaire scores that was not explained by any effects of PAD-IC on walking speed and selected gait parameters assessed before the onset of claudication pain.