Validation of the Vascular quality of life questionnaire – 6 for clinical use in patients with lower limb peripheral arterial disease

BACKGROUND The VascuQoL-6 (VQ-6) health-related quality of life questionnaire, a short version of the disease-specific VascuQoL-25, was developed for clinical practice and use in vascular registries. The study purpose was to evaluate the validity and reliability of VQ-6. METHODS VQ-6 was translated to Norwegian with linguistic validation and face value evaluation, and consecutive patients with intermittent claudication (IC) or critical limb ischemia (CLI) were included. All patients completed VQ-6 and Short Form-36 (SF-36), and were evaluated with ankle-brachial index (ABI) measurement pre- and post-exercise, a constant load treadmill test and clinical consultation at baseline and after 4 weeks. Correlation analysis, change statistics and receiver operator characteristics (ROC) curves were used to evaluate reliability, validity and responsiveness to change. RESULTS One hundred seventy-one patients with peripheral arterial disease (PAD) were included, 70 (41%) female. 147 (86%) of the patients suffered from IC. The reliability of VQ-6 was good, Cronbachs-α 0.82. The ability of VQ-6 to differentiate between IC and CLI was good, area under the curve (AUC) 0.754. There was good correlation between SF-36 physical domains and component scores and VQ-6 score (r = 0.55-0.62) and excellent responsiveness to change after treatment, standard response mean (SRM) 1.12. The clinical anchors of ABI at rest, treadmill walking performance and Fontaine class improvement were less responsive to change than VQ-6, SF-36 and the vascular surgeon's evaluation. CONCLUSIONS VQ-6 is reliable and valid, and can be used to evaluate PAD treatment in clinical practice and in vascular registries. Further research is necessary to determine the clinically important change over time. TRIAL REGISTRATION ISRCTN14846962 (retrospectively registered).