What is the comparison of mortality rates between Central Venous Catheter (CVC) and Arteriovenous Fistula (AVF) for vascular access?

Mortality Rates: CVC vs AVF in Hemodialysis Patients

Arteriovenous fistulas (AVF) are strongly associated with significantly lower mortality rates compared to central venous catheters (CVC), with CVCs conferring approximately 1.5 to 5-fold increased risk of death depending on patient characteristics and catheter type. 1

Mortality Risk Stratification by Access Type

The most recent KDOQI 2019 guidelines explicitly state there is inadequate evidence to make recommendations on choice of vascular access type based solely on mortality associations, despite observational data showing mortality differences. 1 However, this cautious stance reflects concerns about selection bias in observational studies, not an absence of mortality signal.

Quantified Mortality Differences

Recent high-quality cohort data demonstrates:

• 2-year survival rates: AVF 94.1%, tunneled CVC 70.0%, non-tunneled CVC 36.6% 2
• 7-year survival rates: AVF 65.5%, tunneled CVC 26.4%, non-tunneled CVC 11.0% 2
• Adjusted hazard ratios for death: Tunneled CVC carries 2.8-fold increased risk (95% CI 2.0-4.1), while non-tunneled CVC carries 5-fold increased risk (95% CI 3.3-7.6) compared to AVF 2

Earlier landmark studies showed:

• Annual mortality rates: AVF 11.7%, AVG 14.2%, CVC 16.1% 3
• Adjusted relative hazard of death with CVC vs AVF: 1.5 (95% CI 1.0-2.2), with stronger effect in men (RH 2.0) than women (RH 1.0) 3
• Unadjusted hazard ratio for CVC vs AVF: 2.17 (95% CI 1.51-3.11), which remained significant after full adjustment at 1.58 (95% CI 1.01-2.51) 4

Primary Recommendation Framework

KDOQI strongly suggests AV access (AVF or AVG) over CVC in most incident and prevalent hemodialysis patients due to lower infection risk, despite acknowledging insufficient evidence for mortality-based recommendations alone. 1 This apparent contradiction reflects the guideline's emphasis on infection as the primary driver of excess mortality with CVCs.

Infection as Mortality Mechanism

• Bacteremia rates: AVF/AVG 0-11 per 100 patient-years vs CVC 0-19 per 100 patient-years 1
• Pure catheter infection accounts for 2% of deaths, with an additional 10.5% of mortality from catheter infection complicated by cardiovascular disease 4
• Catheter-related bloodstream infections are the leading cause of increased mortality in incident HD patients 5

Clinical Decision Algorithm

For incident hemodialysis patients:

1. First-line: Pursue AVF creation if vessels adequate and life expectancy >1 year 1, 6
2. Second-line: Consider AVG if AVF not feasible due to vessel quality 1, 6
3. Reserve CVC for: Limited life expectancy, multiple failed AV accesses, valid patient preference after informed discussion of risks, or anatomic impossibility 1

For patients starting with CVC:

• Convert to AVF/AVG within first 6 months to minimize mortality risk 7
• Early conversion (first 6 months) shows HR 1.04 (0.97-1.13) vs late conversion (second 6 months) HR 1.23 (1.10-1.38) 7
• KDOQI suggests conversion to reduce infection/bacteremia risk, though acknowledges insufficient evidence for mortality reduction alone within first year 1

Important Effect Modifiers

Age significantly modifies mortality benefit:

• Mortality significantly lower with AVF/AVG vs CVC in patients <80 years old 1
• Findings inconsistent in patients >80 years old, where CVC may be reasonable given limited life expectancy 1

Sex differences exist:

• Increased hazards with CVC vs AVF stronger in men (RH 2.0, p=0.01) than women (RH 1.0, p=0.92) 3
• Women have higher odds of non-AVF access (OR 1.97,95% CI 1.30-3.01) 4

Diabetes and comorbidity burden:

• Higher Charlson Comorbidity Index associated with increased non-AVF use (OR 1.17,95% CI 1.02-1.36) 4
• Elderly women with diabetes show similar outcomes regardless of access type, suggesting CVC may be acceptable 8

Critical Pitfalls to Avoid

Never use subclavian vein for CVC placement in CKD/ESKD patients unless absolutely no alternative exists, as it causes central venous stenosis in 42% and permanently compromises future AVF creation 5

Avoid delayed access planning until dialysis is imminent, which leads to catheter dependence and increased mortality exposure 6, 5

Do not ignore the 70% reality: Over 70% of US dialysis patients initiate with CVC, making early conversion strategy critical 8, 7

Recognize selection bias: Patients with CVC often have older age, female sex, and higher comorbidity burden, which partially explains but does not fully account for mortality differences 4, 2, 3

Quality of Life Considerations

Beyond mortality, AVF provides superior quality of life through:

• Lower hospitalization rates (24% of admissions related to CVC insertion/repair, 10% to catheter infection) 4
• Reduced access interventions (AVF 47-52 per 100 patient-years vs CVC access loss 48-107 per 100 patient-years) 1
• Avoidance of infection-related morbidity and associated disability 1