Self-reported estimation of usual walking speed improves the performance of questionnaires estimating walking capacity in patients with vascular-type claudication.

Objective: Most questionnaires do not estimate the usual walking speed of the patient, although it is well known that patients may experience apparently different walking capacities if walking slow or fast. We hypothesized that correcting the self-reported estimated walking capacity by a coefficient issued from the self-reported estimation of usual walking speed would significantly improve the correlation between questionnaire-estimated and treadmill-measured walking capacity.

Methods: Three hundred ten consecutive patients complaining of vascular-type claudication were asked to estimate their usual walking speed in comparison to people of their age (or friends or relatives) with ratings ranging from much slower (1 pt) to much faster (5 pts), in addition to the filling out of the walking impairment questionnaire (WIQ) and the estimated ambulatory capacity by history questionnaire (EACH-Q). Corrected WIQ (WIQc) and corrected EACH-Q (EACH-Qc) scores were obtained by multiplying the scores of each questionnaire by the "usual-speed" coefficient and dividing by 5. Results for questionnaire scores were compared to maximal walking time (MWT) on a treadmill.

Results: All but four patients self-completed the usual-speed question. Median scores (25-75 centiles) were 41% (26-59) for the WIQ and 24% (11-41) for the EACH-Q. Coefficients of correlation of the three WIQ subscales and of the EACH-Q with treadmill results were significantly improved after correction by the "usual-speed" question. Overall, WIQ (mean of the three WIQ subscales) tended to improve but did not reach significance.

Conclusion: Correcting the self-reported estimation of walking capacity by a self-reported estimation of usual walking pace significantly improves the correlation of all WIQ subscale scores and of the EACH-Q score with treadmill measurements of capacity. This confirms the interest of speed estimation in patients with peripheral arterial occlusive disease and claudication.