Arteriovenous Access Shows Lower Mortality Risk Than Catheters in Hemodialysis

Vascular Access and Survival in Maintenance Hemodialysis

Hemodialysis remains the primary renal replacement therapy for the vast majority of patients with end-stage renal disease [1, 2]. While clinical guidelines emphasize the use of arteriovenous fistulas or grafts, many patients initiate treatment with central venous catheters due to late diagnosis or vascular exhaustion [1, 3]. These catheters are frequently associated with complications such as venous stenosis and systemic infections, which can escalate to life-threatening conditions like sepsis or infective endocarditis [1, 4, 5]. Despite the established preference for permanent access, the degree to which access type independently dictates survival remains a subject of intense clinical debate [2]. A large-scale retrospective analysis now clarifies the survival differences between these modalities, carefully weighing whether the higher mortality seen in catheter users is caused by the device itself or the underlying frailty of the patients who receive them.

Large-Scale Cohort and Statistical Methodology

To evaluate the association between vascular access type and patient survival, researchers analyzed a retrospective cohort of 146,967 incident hemodialysis patients. These individuals initiated treatment between 2016 and 2019 within the clinical network of Fresenius Medical Care North America. This extensive dataset provided the statistical power necessary to examine mortality risks across different access modalities. However, the authors noted a critical confounding factor: patients with central venous catheters often have greater comorbidities than those with arteriovenous access. This disparity in baseline health status frequently complicates causal interpretation, as the higher mortality seen in catheter users may be driven by their underlying illness rather than the access device itself. To address these confounding factors, the study utilized inverse probability treatment weighting (a statistical method that balances the clinical characteristics of different patient groups to mimic a randomized trial). By weighting the data, the researchers sought to isolate the specific effect of the access type on survival outcomes. This approach was supplemented by time-dependent survival analyses, allowing for a precise assessment of how mortality risk evolved over the course of treatment. These rigorous analytic strategies were designed to adjust for relevant confounders and provide clinicians with a clearer understanding of the survival gap between arteriovenous access and central venous catheters in a real-world setting.

Quantifying the Survival Gap by Access Type

The primary analysis revealed a measurable survival advantage for patients who began treatment with an arteriovenous access compared to those using a central venous catheter. For patients initiating hemodialysis with a central venous catheter, the median survival was 1,106 days. In contrast, patients who initiated treatment with an arteriovenous access reached a median survival of 1,290 days, representing a 184-day difference in survival time between the two groups. To further quantify this gap, the researchers calculated the restricted mean survival time ratio (a metric that compares the average time patients in different groups survive within a specific follow-up window). The restricted mean survival time ratio for initiation was 88%, indicating that those starting with a catheter experienced a shorter average survival period during the study interval than those starting with a permanent access. The survival disparities became significantly more pronounced when the researchers conducted a sustained access analysis, tracking patients who remained on their initial access type throughout the study period. In this cohort, the median survival for patients using only a central venous catheter was 448 days, while the median survival for those using only an arteriovenous access was 1,226 days. This resulted in a substantial restricted mean survival time difference of 778 days between the two groups. The restricted mean survival time ratio for sustained access was 52%, suggesting that the average survival time for patients who never transitioned away from a catheter was nearly half that of their counterparts with an arteriovenous access. These figures underscore the clinical correlation between access type and longevity, although the raw differences likely reflect both the physiological impact of the access and the baseline health status of the patients selected for each modality.

Adjusted Mortality Risk and Infection Rates

To account for the inherent differences in baseline health between patients, the researchers applied their inverse probability treatment weighting model. After this adjustment, arteriovenous access initiation was associated with a 25% lower mortality risk compared to catheter initiation, yielding a hazard ratio of 0.75 (95% CI 0.73 to 0.76). The survival benefit appeared even more pronounced in the analysis of long-term use. For patients who maintained their initial access type, sustained arteriovenous access use was associated with a 62% lower risk of mortality, with a hazard ratio of 0.38 (95% CI 0.36 to 0.40). The study also examined specific causes of death to determine if the higher mortality seen with central venous catheters was driven by sepsis or other access-related complications. Surprisingly, the researchers found that infection-related deaths accounted for only 8.6% to 10.6% of deaths across all comparison groups. These differences in infection-related deaths between groups were characterized as small, suggesting that the substantial survival gap between arteriovenous access and catheter use is not primarily explained by infectious complications. Instead, the excess risk associated with catheters likely reflects broader differences in patient selection and baseline health status that persist even after rigorous statistical adjustment.

Clinical Implications of Selection Bias

The researchers concluded that the excess risk associated with central venous catheters at least partially reflects differences in baseline health and patient selection rather than a direct causal effect. While the data demonstrated a clear survival advantage for patients using arteriovenous access, the authors noted that the precise magnitude of any access-related benefit cannot be determined within the constraints of observational data. This distinction is vital for clinicians, as it suggests that the choice of vascular access often serves as a proxy for a patient's overall physiological reserve and clinical stability. Patients who are healthy enough to undergo vascular mapping, survive surgical creation, and maintain a permanent access site likely possess different baseline characteristics than those who require or remain on a catheter. For the practicing nephrologist, these findings indicate that while arteriovenous access remains the preferred modality, the survival gap is not solely a product of the access type itself. Because infection-related deaths accounted for only a small fraction of total mortality across all groups, the substantial risk linked to catheters cannot be fully explained by sepsis or localized complications. Instead, the higher mortality in catheter users is heavily driven by the inherent frailty and comorbid burden of the population that typically receives them. Consequently, the actual survival benefit of transitioning a highly comorbid, medically unstable patient from a catheter to an arteriovenous access may be smaller than the adjusted hazard ratios suggest, reminding clinicians to weigh individual patient prognosis carefully when planning vascular access surgery.

References

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2. Miao P, Tan Z, Yao C, Cai Z, Feng Y, Yu Z. Mortality outcomes associated with vascular access types in hemodialysis for ESRD: a systematic review and meta-analysis.. BMC nephrology. 2025. doi:10.1186/s12882-025-04686-z

3. Slinin Y, Greer N, Ishani A, et al. Timing of dialysis initiation, duration and frequency of hemodialysis sessions, and membrane flux: a systematic review for a KDOQI clinical practice guideline.. American journal of kidney diseases : the official journal of the National Kidney Foundation. 2015. doi:10.1053/j.ajkd.2014.11.031

4. Habib G, Lancellotti P, Antunes MJ, et al. 2015 ESC Guidelines for the management of infective endocarditis. European Heart Journal. 2015. doi:10.1093/eurheartj/ehv319

5. Evans L, Rhodes A, Alhazzani W, et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021. Critical Care Medicine. 2021. doi:10.1097/ccm.0000000000005337