Feasibility and validity of self-reported walking capacity in patients with intermittent claudication

Objective: The primary aim of this study was to assess if self-reported measures of walking limitation correlate better with a community-based assessment of maximum walking distance (MWD) than they do with laboratory-based tests in patients with intermittent claudication. A secondary aim was to examine the effect of prior objective testing on these correlations. Methods: Thirty-one patients completed three self-report tools (self-reported MWD; Walking Impairment Questionnaire [WIQ]; Estimation of Ambulatory Capacity by History-Questionnaire [EACH-Q]) immediately before and approximately 1 week after a series of objective tests (incremental treadmill walking test, 6-minute walk test, 1-hour global positioning system [GPS] recording of a community walk). We analyzed the feasibility of the self-report tools in terms of number of errors and their correlation (r) with objective measures. Results: The correlations of self-report tests to GPS-MWD (range,.579-.808) were consistently higher than with the treadmill test (range,.310-.584) and 6-minute walk test (range,.414-.613). The WIQ had the highest proportion of errors, both at first and second completion (58% and 42%, respectively), compared with self-reported MWD (23% and 13%, respectively) and the EACH-Q (6.5% and 13%, respectively). Correlations were improved with the second set of self-report tests (range, .310-.595 to .414-.808). Conclusions: The fact that all self-report tools correlated better with a community-based measure of MWD using GPS than with laboratory results confirms that they measure what they aim to: community-based MWD. In addition, prescription of a community walk might help patients to better estimate their walking limitation. (J Vasc Surg 2013;57:1227-34.)