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

Abstract

BackgroundThe 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.MethodsVQ-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.ResultsOne 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.ConclusionsVQ-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).

Self-reported health status and disease-specific quality of life one year after treatment for peripheral arterial disease in clinical practice

“…To use the self-reported health status, SF-36 item 2, after one year to estimate MID will probably be wrong, as the recall bias will be too large. But, the improvement in VQ-6 summary score for the "unchanged" group (2.3) supports that the earlier proposal of two points of change as indicative and four points as a certain change [4].…”

“…A population-based study from the Swedish national vascular registry, Swedvasc, has indicated 1.7-2.2 scale steps as a minimally important difference (MID), and 3.5-4.5 scale steps as a substantial clinical benefit [7]. MID was estimated using two different methods in the validation study [4]. One method (0.5 SD) gave a value of 1.725 scale points, the other (95%CI) 0.82 for improvement and − 1.38 for deterioration [23,24].…”

“…In item one, the patients report some confusion regarding the content of the term "activities" [19]. This term was broadened in the Norwegian translation to "activities and daily activities of living" after the cognitive evaluation by patients and health professionals [4]. The number of patients lost to follow up at one year reflects both the increased mortality and morbidity associated with this disease, also among patients with presumptive stable disease [1,25], as well as the advanced age of the patients.…”

“…The inclusion period ran from August 2014 to August 2015. Inclusion, exclusion and follow-up of patients are described in detail in a previously published paper [4], and summarized in Fig. 1.…”

“…VascuQoL-6 (VQ-6) is a short version of the disease-specific quality of life instrument VascuQoL-25 [ 2 , 3 ], intended both for intermittent claudication (IC) and critical limb ischemia (CLI). VascuQoL-6 was found to be valid, reliable and responsive to change [ 4 ]. The VascuQoL-6 study aimed both to validate the VQ-6-instrument based on registrations at baseline and after 4 weeks, and to investigate the development in self-reported health status, measured with SF-36, and disease-specific QoL, measured with VQ-6, after one year for consecutive patients treated for peripheral arterial disease in clinical practice.…”