Hemodialysis Patients Aged 80+ Benefit From Switch to AVFs

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Elderly patients who start dialysis with a central venous catheter but convert to an arteriovenous fistula within the first year lower their death risk significantly.
Elderly patients who start dialysis with a central venous catheter but convert to an arteriovenous fistula within the first year lower their death risk significantly.

Among patients aged 80 years and older initiating hemodialysis, those who converted from a central venous catheter (CVC) to an arteriovenous fistula (AVF) for vascular access within the first year of dialysis had a mortality risk similar to those who initially used an AVF, a new study found. They had a lower mortality risk than patients who continued to use a CVC.

A team led by Kamyar Kalantar-Zadeh, MD, MPH, PhD, of the University of California Irvine, examined vascular placement access and mortality among 8356 incident hemodialysis (HD) patients aged 80 years and older who were alive for at least 1 year. Over the first year of HD, 27% of patients persisted in CVC use only, 36% underwent placement of an AVF from a CVC, 13% underwent placement of an arteriovenous graft (AVG) from a CVC, 18% used an AVF initially, and 6% used an AVG initially, the investigators reported in Nephrology Dialysis Transplantation.

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The cohort had a median follow-up of 23 months. Over a follow-up period of 9808 person-years, 3410 deaths occurred. Compared CVC use only (reference), conversion from a CVC to an AVF was associated with a significant 21% decreased risk of death in a model adjusting for case-mix and albumin concentration. Patients who initiated HD with an AVF or AVG had a significant 27% and 18% decreased risk of death, respectively. Dr Kalantar-Zadeh and his colleagues found no significant change in mortality among patients who converted from a CVC to an AVG.

“To our knowledge, this is the first study to demonstrate that elderly patients who initiated hemodialysis with CVCs yet underwent placement of an AVF within 1 year had similar survival compared with those who initiated dialysis using AVFs as their primary vascular access,” the authors stated.

The study also showed that longer duration of CVC use within the first year of HD was associated with greater death risk. For example, compared with CVC use for less than 3 months (reference), CVC use for 9–12 months was associated with a significant 28% increased risk of death.

Dr Kalantar-Zadeh's team explained that although use of AVFs is associated with better clinical outcomes in the general HD population, their use in elderly HD patients presents unique challenges because of their higher rates of inadequate maturation of vascular access and limited life expectancy.

Strengths of the study included the use of a large, nationally representative cohort of dialysis patients and comprehensive availability of detailed, longitudinally patient-level comorbidity, laboratory, and dialysis-treatment data, including type of vascular access, Dr Kalantar-Zadeh and his collaborators said. With regard to limitations, they pointed out that they did not have information on the status of access such as blood flow rate and secondary vascular access complications. In addition, due to data limitations, they could not examine cause-specific mortality “to better elucidate underlying mechanisms of the vascular access type-mortality association,” they noted.

Reference

Ko GJ, Rhee CM, Obi Y, et al. Vascular access placement and mortality in elderly incident hemodialysis patients. Nephrol Dial Transplant. 2018; published online ahead of print.

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