PXDN and peripheral arterial disease: In order to determine whether VPO1 is actually a non-invasive marker, mediator and predictor of disease, as well as to determine to what extent assessment of VPO1 might contribute to risk profiling in patients with PAD, further prospective studies are necessary to elucidate associated comorbidities, as PAD as well as CKD have multifactorial etiologies.