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

Abstract

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).

Keywords: Endovascular procedures; Intermittent claudication; Patient reported outcome measures; Peripheral arterial disease; Quality of life; Vascular surgical procedures.

Conflict of interest statement

Ethics approval and consent to participate

The Regional Committee for Medical and Health Research Ethics approved the study (reference number 2014/221). License to use SF-36v1 were given from Optuminsight Life Sciences, Inc. (QM020601). Permission to translate and use VQ-6 was given by the original developers: MM (copyright) and JN.

All patients provided written informed consent.

Consent for publication

Not applicable.

Competing interests

MM has copyright to the VascuQoL-25 and VascuQoL-6, and must be contacted prior to use. He received no financial reimbursement in relation to this study. ASFL is a board member of the Norwegian vascular registry (NORKAR). JN has acted as chairman of the Swedish vascular registry (Swedvasc). No other potential conflict of interests is stated by the authors.

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Figures

Fig. 1

Inclusion and exclusion of patients in the VascuQoL-6 study. PAD –Peripheral arterial disease, IC-intermittent claudication, CLI –critical limb ischemia

Fig. 2

SF-36 subscale mean scores at baseline (n = 171). Patients suffering from intermittent claudication (IC) and critical limb ischemia (CLI). For comparison Norwegian norm population aged 60 years and over (Loge 1998). PF - physical functioning, RP - physical role limitations, BP - bodily pain, GH - general health, VT - vitality, SF - social functioning, RE - emotional role limitations, MH - mental health

Fig. 3

Sensitivity to disease severity. Receiver operator characteristics (ROC) curve of VQ6 summary score at baseline (n = 171)

Fig. 4

Responsiveness to change. Receiver operator characteristics (ROC) curve of VQ6 summary score change compared to clinical improvement as evaluated by the vascular surgeon, improvement of ABI at rest > 0.1, improvement in treadmill walking distance of more than 50% and improvement in Fontaine class

Fig. 5

Responsiveness to change. Standard response mean (SRM) of SF-36, domains and component summary scores, and VQ6, all items and summary score