Is the Walking Impairment Questionnaire a surrogate marker of 6-minute walking test performance in patients with peripheral artery disease with different degrees of claudication symptoms?

AIM: To analyze the associations between the Walking Impairment Questionnaire (WIQ) and 6-minute walk test (6MWT) in absolute or relative performance in patients with peripheral artery disease (PAD) and different degrees of claudication symptoms.

METHODS: Two hundred and sixty-seven patients with PAD and claudication symptoms participated in the study. All patients underwent 6MWT and WIQ tests. Patients were divided into tertile groups according to their 6MWT performance (1st tertile = severe, 2nd = moderate, 3rd = mild). Multiple linear regression was performed to investigate the association between WIQ scores and the achievement of expected performance in the 6MWT.

RESULTS: Claudication onset distance and time, total walking distance, and the percentage of the predicted values had a significant weak correlation ( P  < 0.01) with WIQ scores (distance, speed, and stair-climbing capacity). The correlations for almost all variables were slightly higher in the 1st tertile compared with the 2nd and 3rd tertiles (i.e. WIQ-distance and Claudication onset time, r  = 0.25 and 0.12, WIQ-distance and Claudication onset distance, r  = 0.34 and 0.18; WIQ-distance and total walking distance, r  = 0.23 and 0.18, respectively). Multilinear regression confirmed a slightly superior relationship in the 1st tertile compared with the 2nd tertile (i.e. WIQ-distance and Claudication onset time, R2  = 0.24 and R2  = 0.01; WIQ-distance and Claudication onset distance, R2  = 0.25 and R2  = 0.03, respectively).

CONCLUSIONS: WIQ is weakly associated with absolute and relative 6MWT performance in patients with PAD. Despite slightly better correlations in patients with severe claudication symptoms, WIQ scores must be used with care as a surrogate marker of 6MWT performance in this group.