The clinical utility of a six-minute walk test in peripheral arterial occlusive disease patients

OBJECTIVES: To determine the test-retest reliability of the distance covered and the steps taken to complete a 6-minute walk test by peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. To determine the relationship between the total distance and steps covered during the 6-minute walk test and clinical measures of PAOD severity. DESIGN: Cross-sectional design. SETTING: The Claude Pepper Older Americans Independence Center at the University of Maryland at Baltimore. PARTICIPANTS: Sixty-four PAOD patients between the ages of 45 and 88 years (age = 68 ± 7 years, ankle/brachial index (ABI) = .61 ± .19) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. MEASUREMENTS: Patients were assessed on a 6-minute walk test and a treadmill graded exercise test. A second 6-minute walk test was administered approximately 1 week later. Patients also were characterized in regard to blood pressure in the arms and legs, ABI, anthropometry, body composition, and physical activity. RESULTS: The distances walked during the two 6-minute walk tests were similar (350 ± 78 m vs 360 ± 73 m), resulting in a high reliability coefficient (R = .94) and a low coefficient of variation (10.4%). The total steps taken during the 6- minute walk test also were similar (562 ± 113 steps vs 387 ± 107 steps), resulting in a high reliability coefficient (R = .90) and a low coefficient of variation (11.7%). Furthermore, the 6-minute walking distance correlated with the distances to onset (r = .346, P = .007) and with maximal claudication pain (r = .525, P < .001) during the treadmill test as well as with ABI (r = .552, P < .001). CONCLUSION: The 6-minute walk test yields highly reliable measurements, which are related to the functional and hemodynamic severity of PAOD, in patients with intermittent claudication.