The association of mineral metabolism with vascular access patency.

Abstract

Declining kidney function leads to progressively dysregulated mineral homeostasis and contributes to vascular calcification and a pro-inflammatory milieu, both of which play a critical role in loss of dialysis vascular access patency. We designed this study to examine the relationship between markers of bone and mineral metabolism, vitamin D replacement medications, and vascular access outcomes. We hypothesized that higher levels of calcium, phosphorous, parathyroid hormone (PTH), and albumin are independently associated with vascular access patency and that vitamin D supplementation is associated with lower risk of access failure. We abstracted data on 204 consecutive patients referred for angiographic evaluation of their permanent arteriovenous access over a 25-month period. We followed patients from the time of access salvage until subsequent referral for access failure. The incidence of vascular access failure did not differ by serum phosphorus, PTH, calcium, calcium-phosphorus product or albumin level. Patients receiving any vitamin D replacement therapy, however, had a lower incidence of access failure compared to those receiving no therapy. Those receiving vitamin D3 therapy with or without paricalcitol (Zemplar, Abbot Laboratories, Abbot Park, IL) or calcitriol had an adjusted HR = 0.18 compared to those receiving no vitamin D therapy. This study suggests a relationship between vitamin D3 usage and better vascular access patency, independent of the effect of vitamin D on PTH. Though this relationship needs more rigorous investigation prior to clinical application, the known differences in the pro- and anti-inflammatory effects of various vitamin D metabolites provide a potential mechanism for these clinical observations.