Development and validation of the Patient Benefit Index for peripheral arterial disease Translated title: Development and validation of the Patient Benefit Index for peripheral arterial disease

Abstract

Abstract. Background: The aim of this study was to develop and validate a specific Patient Benefit Index (PBI) version for the treatment of peripheral arterial disease (PAD). Patients and methods: A non-interventional longitudinal development study was conducted. The first phase comprised a qualitative pre-study with n = 50 patients, in which the PBI was adapted for peripheral arterial disease. The resulting Patient Benefit Index for peripheral arterial disease (PBI-PAD) was validated in the second phase at two points of measurement. The total PBI-PAD score was calculated by weighting item-wise the achievement of treatment goals with the initially assessed needs. Feasibility, internal consistency, and construct validity were analysed and the generic three level version of the EuroQol five-dimensional questionnaire (EQ-5D-3L) and the disease-specific instrument Vascular Quality of Life Questionnaire (VascuQoL) were used for convergent validation. Results: In the pre-study, the PBI-PAD, consisting of 12 items, was developed. N = 103 patients participated in the main study. At T2, data were available for n = 57 patients. Mean age was 71.0 years ± 9.1 and 66.7 % of the participants were male. The amount of missing values of the PBI-PAD score was low (< 4.0 %) and no relevant floor effects were observed. Both parts of the PBI (needs at T1 and benefits at T2) were internally consistent with Cronbach’s alpha > 0.7. PBI-PAD total score correlated significantly with the T2-T1-differences of the EuroQol-visual analogue scale (EQ VAS) (r = 0.4, p = 0.007) and the Vascular Quality of Life Questionnaire (r = 0.5, p < 0.001). Conclusions: The PBI-PAD is a feasible, internally consistent, and valid instrument to assess patient-relevant benefits in PAD patients receiving minimally invasive treatment or surgical procedures. It can be recommended for use in routine care as well as in clinical studies.