Maturation and Patency Rates of AVF HD Access

Among the population of patients with kidney failure, the creation and maintenance of a functional arteriovenous hemodialysis access remains a concern. The National Kidney Foundation’s (NKF) Dialysis Outcome Quality Initiative originally recommended use of the autogenous arteriovenous fistula (AVF) over the prosthetic alternative arteriovenous graft and a tunneled dialysis catheter (TDC) due to benefits of an AVF, including improved patency, decreased morbidity, decreased mortality, and cost.

The NKF guidelines called for a target incidence of ≥50% and prevalence of >40% for AVFs in the United States. The Centers for Medicare & Medicaid Services implemented the National Access Vascular Initiative (2003-2006), the Fistula First Breakthrough Initiative for AVFs with an updated prevalence target of 66% by 2009. The increased emphasis on AVFs resulted in a higher rate of nonmaturation and TDC use in the United States.

The high maturation failure rate led the national Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases to create the Hemodialysis Fistula Maturation (HFM) Consortium, a group of seven clinical centers charged with examining the influences of vascular anatomy bioloigy, clinical attributes, and healthcare processes on AVF maturation.

The HFM data set included patients with dialysis-dependent kidney failure and those with predialysis chronic kidney disease (CKD). Thomas S. Huber, MD, PhD, and colleagues conducted a case series analysis to examine AVF maturation, longer-term patency, and remedial procedures to facilitate maturation, manage complications, or maintain patency in the HFM cohort. Results were reported in JAMA Surgery [2021;156(12):1111-1118].

A total of 602 participants with kidney failure or CKD were enrolled in the HFM study; of those, 535 were included in the case series analysis. The primary outcome of interest was unassisted maturation of the AVF. Kaplan-Meier analyses were used to summarize functional patency, freedom from intervention, and participant survival.

Of the 535 participants, 66.0% (n=353) had kidney failure and 34.0% (n=182) had CKD. The cohort included 372 men (69.5%) and 163 women 30.5%); mean age was 54.6 years, and 58.1% (n=311) had diabetes. Overall, the racial distribution was relatively equal; 45.4% (n=243) were Black, 45.6% (n=244) were White, and 9.0% (n=48) were other. There was racial variation in dialysis status: kidney failure, Black 50.4% (n=178), White 39.9% (n=141);  CKD, Black 35.7% (n=65), White 56.6% (n=103).

Overall, mean body mass index was 30.3 kg/m2; 25.2% (n=135) had coronary artery disease and 14.4% (n=77) had peripheral artery disease. Most of the participants with kidney failure were undergoing dialysis through a TDC at study enrollment, and nearly one-third (115 [32.6%]) had a prior permanent access. The target cannulation site for 64% (n=342) of study access procedures involved the upper arm; the brachial/ulnar/radial-cephalic configuration was the most common (kidney failure, 36.8%; CKD, 47.8%). The groups were similar in the frequency of the forearm radial/ulnar-cephalic access, but the incidence of brachial/radial/ulnar-basilic/brachial appeared to be higher among participants with kidney failure (90 [25.5%]) compared with the group with CKD (35 [19.2%]).

The maturation rates for participants with kidney failure versus participants with CKD were 29% versus 10% at 3 months, 67% versus 38% at 6 months, and 76% versus 58% at 12 months. Approximately one-third of participants in both groups underwent intervention to facilitate maturation or manage access complications before ascertainment (kidney failure group: 37.7%, n=133; CKD group, 34.6%, n=63). The most common intervention for both groups was for AVF stenosis (kidney failure, 26.3%; CKD, 22.5%). Other interventions to facilitate maturation or manage complications were substantially less common (access vein branch > central vein stenosis > thrombosis) and did not differ meaningfully between the two groups.

In the group with kidney failure, 49% successfully used their AVFs without intervention at 12 months, and 27% underwent an intervention before successful maturation. In the CKD group, maturation was expectedly delayed, with 39% achieving unassisted maturation and 19% achieving assisted maturation at 12 months.

Median time from access creation to maturation was 115 days overall, but differed by initial indication: CKD, 170 days; kidney failure, 105 days. Participants with kidney failure required a TDC for a mean of 2.9 months prior to access ascertainment. In the group with kidney failure, 37.7% (n=133) required at least one inpatient hospitalization for any cause before AVF ascertainment, as did 33.5% (n=61) of those in the group with CKD.

The functional patency for the AVFs that matured at 1 year was 87% (95% confidence interval [CI], 83.2%-90.2%) and 75% at 2 years (95% CI, 69.7%-79.7%). There was no significant difference in functional patency between those that received interventions before maturation and those that did not receive interventions. Nearly half (47.5%, n=188) of the AVFs that matured had further intervention to maintain patency or treat complications.

The researchers cited some limitations to the study, including the study being performed by clinicians with a dedicated interest in hemodialysis access, primarily at academic medical centers. Because the primary objective was to identify predictors of AVF maturation, participants were all considered reasonable candidates for creation of an AVF. Enrollment criteria may have been liberalized, resulting in enrollment of participants with a low likelihood of successful maturation. However, the rate of early thrombosis (5.3% within 18 days) and the rate of maturation were good and consistent with other reports. Also, the maturation end point was indeterminant in a small proportion of participants who were excluded from the analysis; their outcomes could have affected the results. Finally, the HFM study only included single-stage AVF procedures despite the increasing application of a 2-stage brachial basilic approach.

In conclusion, the authors said, “The findings of this study suggest that the AVF remains a reasonable option for patients who require access for hemodialysis access, although both their maturation and continued use require a moderate number of interventions to maintain patency and treat associated complications.”

Takeaway Points

  1. The use of autogenous arteriovenous fistulas (AVFs) for hemodialysis access is recommended by national guidelines; researchers conducted a case series analysis to examine AVF usability, longer-term functional patency, and rates of interventions to facilitate maturation and manage
  2. Maturation rates for participants with kidney failure were 67% at 6 months and 76% at 12 months; nearly one-third required an intervention to facilitate maturation or manage a complication.
  3. The study findings suggest that maturation and patency rates are suboptimal, but reasonable considering the alternatives.