Standardized Definitions for Hemodialysis Vascular Access

Abstract

Vascular access dysfunction is one of the leading causes of morbidity and mortality among end-stage renal disease patients 1,2. Vascular access dysfunction exists in all 3 types of available accesses: arteriovenous fistulas, arteriovenous grafts, and tunneled catheters. In order to improve clinical research and outcomes in hemodialysis access dysfunction, the development of a multidisciplinary network of collaborative investigators with various areas of expertise, and common standards for terminology and classification in all vascular access types is required. The North American Vascular Access Consortium (NAVAC) is a newly formed multidisciplinary and multicenter network of experts in the area of hemodialysis vascular access, who include nephrologists and interventional nephrologists from the United States and Canada with: (1) a primary clinical and research focus in hemodialysis vascular access dysfunction, (2) national and internationally recognized experts in vascular access, and (3) a history of productivity measured by peer-reviewed publications and funding among members of this consortium. The consortium’s mission is to improve the quality and efficiency in vascular access research, and impact the research in the area of hemodialysis vascular access by conducting observational studies and randomized controlled trials. The purpose of the consortium’s initial manuscript is to provide working and standard vascular access definitions relating to (1) epidemiology, (2) vascular access function, (3) vascular access patency, and (4) complications in vascular accesses relating to each of the vascular access types.

Cumulative Patency of Contemporary Fistulas versus Grafts (2000–2010)

“…The primary outcome, cumulative patency, was defined as time from initial access creation to permanent failure (30,31). An access was defined as a primary failure if it was unable to provide prescribed dialysis via two-needle cannulation consistently for 1 month within 6 months of its creation, despite interventions to facilitate maturation (31).…”

“…An access was defined as a primary failure if it was unable to provide prescribed dialysis via two-needle cannulation consistently for 1 month within 6 months of its creation, despite interventions to facilitate maturation (31). This included accesses that had early failures for technical reasons, such as perioperative complications or early postcreation thrombosis, or those that simply did not dilate, were too frail to be cannulated, or "failed to mature."…”

Novel Therapies for Hemodialysis Vascular Access Dysfunction

“…Ultrasonographic characteristics, such as blood flow rate and vessel diameter within the first few months after AVF creation, have been proposed as surrogate outcomes for evaluating AVF maturating-enhancing interventions. Although clinical practice guidelines recommend the use of ultrasound for early clinical assessment of AVF maturation (94), the suitability of ultrasonographic parameters as surrogate outcomes for clinical trials is not known. In the National Institutes of Health-sponsored Hemodialysis Fistula Maturation (HFM) Study, a prospective, multicenter, observational study that is currently underway, serial ultrasounds are being performed at uniform time points after AVF creation (95).…”

Peripherally Inserted Central Catheters and Hemodialysis Outcomes

“…Vascular access was determined by the modifier codes on individual HD treatment claims. Conversion to fistula or graft access was defined as the first day of the first 30-day period in which all available vascular access modifiers on all HD treatment claims were for AVF only (modifier V7) or AVG only (modifier V6) with no intervening codes for catheter use (modifier V5) on the basis of established working definitions for a working AVF (19,20).…”