Comparison of generic and disease-specific questionnaires for the assessment of quality of life in patients with peripheral arterial disease

Objective: This study compared the ability of generic and disease-specific questionnaires to assess quality of life (QOL) at baseline and to detect change in QOL after treatment in patients with peripheral arterial disease (PAD). Methods: This prospective multicenter trial recruited 514 patients with PAD who needed an imaging workup and had an ankle brachial pressure index of less than 0.90. Patients with severe comorbidity were excluded, leaving a study population of 450 patients. Patients completed two generic questionnaires, the Short Form 36 (SF-36) and the European Quality of Life 5D (EuroQol-5D), and one disease-specific questionnaire, the Vascular Quality of Life (VascuQol) at baseline and after 6 months of follow-up. Rutherford classification and treadmill walking distance were determined at baseline and after 6 months of follow-up and were considered indicators of disease severity. Receiver operating characteristic (ROC) curves and areas under the curves (AUCs) were used to evaluate each of the three questionnaires for its ability to discriminate between severe and mild disease at baseline and to discriminate between a large and small change in disease severity after follow-up. The underlying assumption was that disease severity is a major determinant of QOL. This implies that the validity of a QOL questionnaire is reflected by its ability to discriminate between mildly and severely diseased patients. Results. At baseline, 443 patients and after follow-up, 386 patients completed questionnaires. At baseline, no significant (P >.05) differences were observed among AUCs for the total scores of the three questionnaires, indicating that all three questionnaires assessed the disease severity equally well. After follow-up, the AUCs for the VascuQol were significantly higher than the AUCs for the SF-36 and EuroQol-5D with respect to detection of improvement in Rutherford classification (P <.05), indicating that change in disease severity after follow-up was best detected by the VascuQol. Conclusion: The VascuQol is the preferred questionnaire as outcome measure for QOL in future trials and clinical follow-up of patients with PAD.