A National Study of Autogenous Arteriovenous Access use and Patency in a Contemporary Hemodialysis Population

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In Review
Stoumpos,S. "A National Study of Autogenous Arteriovenous Access use and Patency in a Contemporary Hemodialysis Population". Journal of Vascular Surgery. 2018. :.
PubMed • Full text

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Clinical Question

Given the significant advances in modern practice, in current hemodialysis patients, what are expected patency rates, predictors of primary AV graft failure, and efficacy of interventions to prolong patency?

Bottom Line

Despite interventions and competing-risks analysis, fistulas continue to have high rates of failure.

Major Points

Creating an arteriovenous (AV) fistula for hemodialysis is a complex process requiring consideration of a patient's prognosis, anatomy, and risk factors for complication. The rates of primary patency, as well as patency following intervention to preserve the initial site of fistula creation, are not known. This was a prospective national cohort study in Scotland of all AV fistulas created in 2015 and followed through the end of 2016. The study benefitted from a high rate of follow-up and high degree of specificity regarding patency and the interventions to maintain such patency. The paper's major findings include a baseline high rate of primary failure, as well as high progression of stenosis to thrombosis. Subanalysis conclusions regarding superiority of upper arm to forearm are somewhat short sited in that the preference for forearm creation preserves proximal anatomy in the event of future failure, an aspect of management not addressed in the paper.

Guidelines

The Kidney Disease Outcome Quality Initiative Recommendations for Access Preference [1] run counter to some of the paper's conclusions. In particular this analysis recommends forearm fistula first to preserve proximal vasculature. Recommended guideline order of preference is as below:

  • 1. Radiocephalic
  • 2. Brachiocephalic
  • 3. Brachial-basilic
  • 4. Upper extremity brachial cephalic prosthetic

Design

  • National multicenter cohort study undergoing AV access creations in 2015 using data from the Scottish Renal Registry
  • N = 537 patients, 582 fistulas
  • Setting: All (9) Renal units in Scotland
  • Enrollment: 2015
  • Mean followup: 11.8 months (through December 31, 2016)
  • Analysis: Kaplan-Meier, for primary, primary assisted, and secondary patency. Cox PH for time to final failure/access abandonment. Cumulative Hazard for AV access failure. Competing risk regression for cumulative incidence of AV access failure (competing events defined as death, kidney transplant, or switch to peritoneal dialysis)
  • Patients censored at death, kidney transplant, switch to peritoneal dialysis, or loss to follow-up
  • Primary outcome: Successful AV access use for 30 days, Rates of primary, primary assisted, and secondary patency at one year

Population

Inclusion Criteria

  • Adults
  • Underwent autogenous AV access creation in 2015 in Scotland

Exclusion Criteria

  • Nonautogenous AV accesses
  • Fistula not in arm

Baseline Characteristics

General population (N = 537)

  • Male 60.1%
  • White 95.7%
  • Comorbidities
    • Diabetes 41.5%
    • Cardiovascular Disease 20.9%
    • Cerebrovascular disease 11.5%
    • Peripheral vascular disease 11.5%
  • Charlson Comorbidity Index
    • 2 30.2%
    • 3-4 36.9%
    • >4 32.9%
  • AVF procedures (N= 582)(mean±SD)
  • Age at AVF creation 60±14
    • >= 60 years 51.4%
  • Duration of follow-up 11.8±7.6
  • >= 12 months 56.9%
  • >= 18 months 24.9%
  • BMI 28.6±6.9
  • Hemodialysis at AVF creation 46.6%
  • Hemodialysis vintage, months, median (IQR) 7.6 (2.6-27.5)
  • Antiplatelet use 45.7%
  • Anticoagulant use 7.7%
  • Previous AV Access 28.2%
  • Previous CVC Use 45.7%

Interventions

Total AVFs (N = 582)

  • AVF Use
    • Successful AVF 55.3%
    • AVF Nonuse 28.5%
    • Indeterminate 16.2%
  • Natural history after AVF creation
    • AVF functional 41.9%
    • AVF patent 7.4%
    • AVF abandonment 33.7%
      • Primary failure 29.7%
      • Late failure 4.0%
    • Death 8.2%
    • Transplantation 7.6%
    • Peritoneal dialysis 0.9%
    • Loss to follow-up 0.3%
  • Interventions (Procedures = 275, Interventions per patient-year = 0.48)
    • Angioplasty 67.8%
    • Stent insertion 4.0%
    • Thrombectomy 4.4%
    • Revision 10.5%
    • Ligation of tributaries 13.5%
  • Location of Intervention
    • Inflow artery 7.7%
    • Outflow vein 63.1%
    • Swing Point 20.9%
      • Juxta-anastamotic 18.5%
      • Cephalic arch 2.4%
    • Central vein 8.3%
  • Indeterminate = functional status could not be determined as patient did not initiate dialysis, died, or were transplanted

Outcomes

Primary Outcomes

Primary outcome 1 year outcomes: Primary patency 48%, primary assisted patency 67%, secondary patency 69% 55.3% successfully used for hemodialysis, 28.5% not used, 16.2% indeterminate

1 Year Patency Outcomes
Pooled Primary Patency 48% ( 95% CI 44-52%)
Primary Assisted Patency 67% (95% CI 63-71%)
Secondary patency 68% (95% CI 65-73%)

Subgroup Analysis

Upper arm vs. Forearm AV access

  • Comparisons are Upper arm vs. Forearm
1 Year Patency Outcomes
Pooled Primary Patency 51% (95% CI 45-56%) vs. 43% (95% CI 35-50%)
Primary Assisted Patency 73% (95% CI 68-77%) vs. 55% (95% CI 48-62%)
Secondary Patency 74% (95% CI 70-79%) vs. 58% (95% CI 51-65%)

Brachial-Cephalic vs. Brachial-Basilic

  • Comparisons are Brachial-Cephalic vs. Brachial-Basilic
1 Year Patency Outcomes
Pooled Primary Patency 57% (95% CI 51-63%) vs. 35% (95% CI 26-45 %)
Primary Assisted Patency 77% (95% CI 72-82%) vs. 62%(95% CI 52-71%)
Secondary Patency 80% (95% CI 75-85%) vs.65 % (95% CI 55-73%)

Cox PH Analysis of Factors Associated with Patency

Univariate analysis

  • Prolonged secondary patency
    • Upper arm AV access (hazard ratio [HR], 0.54; 95% CI, 0.41-0.72)
  • Reduced Secondary Patency
    • Previous AV access (HR, 1.50; 95% CI, 1.11-2.01)
    • Previous ipsilateral CVC (HR, 1.44; 95% CI, 1.02-2.03)

Multivariate Analysis

  • Prolonged Secondary Patency
    • Upper arm AV access (HR, 0.48; 95% CI, 0.36 to 0.65)
  • Reduced Secondary Patency
    • Previous AV access (HR, 1.49; 95% CI, 1.06 to 2.07)

Adverse Events

  • as above

Criticisms

  • Upper extremity fistulas exclude possibility of use of distal areas in event of failure (unaccounted for in statistical analysis)
  • No universal pre-operative imaging screening
  • No universal duplex ultrasound surveillance
  • Relatively low rates of diabetes and peripheral vascular disease

Funding

  • Investigator Research grant from Proteon Therapeutics

Further Reading

  1. ↑ Navuluri R & Regalado S The KDOQI 2006 Vascular Access Update and Fistula First Program Synopsis. Semin Intervent Radiol 2009. 26:122-4.
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