The Clinical and Economic Effect of Vascular Access Selection in Patients Initiating Hemodialysis with a Catheter

A practical review of barriers and challenges to a definitive randomised trial of grafts versus fistula

A definitive randomised controlled trial of arteriovenous fistula (AVF) versus arteriovenous grafts (AVG) has been advocated for more than a decade, but as yet, none has been completed. The aim of this article is to summarise the theoretical barriers, review the difficulties in trial design and practicalities that have thus far prevented this from occurring.

Factors Associated with the Initial Vascular Access Choice and Median Utilization Time in Hemodialysis Patients

The aim of the study was to elucidate predictors associated with the initial choice of vascular access (VA) type. The secondary aim was to determine the initial VA's median utilization time and the factors governing it. This prospective cohort study included 387 hemodialysis (HD) patients admitted to the Clinic for Hemodialysis, Clinical Center University of Sarajevo, in consecutive order between January 2006 and December 2016. We selected the primary predictors for the initial VA type using a random forest algorithm. We further quantified factors governing the initial choice of VA: temporary catheters (TCs), compared to arteriovenous fistula (AVF), using multivariate logistic regression. Finally, we used log-rank and Cox regression models to estimate the median time on each initial VA and find predictors governing it. Of the 387 patients, 265 (68.5%) used TC at dialysis initiation and 122 (31.5%) AVF. Predictors of the TC's versus AVF's initial use were older age (odds ratio = 1.02; confidence interval [CI] = 1.0, 1.03; P = 0.03) and primary cause of chronic kidney disease, particularly diabetes, compared to all other causes of kidney disease. Median time on initial AVF was 57.0 months (95% CI = 36.9, 64.1), and on initial TC 4.99 months (95% CI = 2.69, 8.48). Younger age (hazard ratio [HR] = 0.98; 95% CI = 0.97, 0.99; P = 0.01), male sex (HR = 1.51; 95% CI = 1.05, 2.19; P = 0.03), and hypertension (HR = 1.63; 95% CI = 1.13, 2.36; P = 0.01) predicted median time on initial TC, while older age (HR for patients aged > 70 years = 1.86; 95% CI = 1.09, 3.17; P = 0.02), and diabetes (HR = 1.97; 95% CI = 1.19, 3.24; P = 0.01), predicted median time on initial AVF. These results point to late VA referrals and delays in transitioning to permanent VA.

Assessing the Value of Further Investment in R&D Using Mixed Methods: A Case Study of Biosensor-Integrated Arteriovenous Grafts

This study illustrates the utility of a mixed-methods approach in assessing the value of an example novel technology-biosensor-integrated self-reporting arteriovenous grafts (smart AVGs). Currently in preclinical development, the device will detect arteriovenous graft stenosis (surveillance-only use case) and treat stenosis (interventional use case). The approach to value assessment adopted in this study was multifaceted, with one stage informing the next and comprised a stakeholder engagement with clinical experts to explore the device's clinical value, a cost-utility analysis (CUA) from a US Medicare perspective to estimate pricing headroom, and an investment model estimating risk-adjusted net present value analysis (rNPVs) to determine commercial viability. The stakeholder engagement suggested that it would currently be difficult to establish the current value of the surveillance-only use case due to the lack of well-established interventions for preclinical stenosis. Based on this, the CUA focused on the interventional use case and estimated economically justifiable prices at assumed effectiveness levels. Using these prices, rNPVs were estimated over a range of scenarios. This value assessment informs early decision-making on health technology R&D by identifying the conditions (including clinical study success, potential market size and penetration, market access strategies, and assumptions associated with CUA) under which investment may be considered attractive.

Routine Clinic Surveillance on Arteriovenous Graft Patency in Hemodialysis Patients with Previous Access Complications

Background: Arteriovenous grafts (AVGs) are an alternative for hemodialysis (HD) access in patients with inadequate vasculature or advanced age. The effect of routine surveillance for AVG maintenance remains unclear. This study assesses the clinical and economic outcomes of routine surveillance at a collaborative clinic in patients with previous access complications. Methods: We recruited HD patients from the initiation of the clinic in 2020, and divided them into two groups: those receiving routine surveillance and those without. Primary outcomes included AVG interventions (e.g., arteriovenous access [AVA] reconstruction, graft-anastomosis stenting, percutaneous transluminal angioplasty [PTA]). Other outcomes included AVG secondary patency and costs associated with the interventions. Results: Twenty-two patients with routine surveillance and 65 without were recruited. There was no significant difference in AVA reconstruction rate between the surveillance and non-surveillance groups (0.46 vs. 0.5 per 100 patient-months, p = 0.99), however, rates of graft-anastomosis stenting (0.66 vs. 0.2 per 100 patient-months, p = 0.02) and PTA (30.19 vs. 14.17 per 100 patient-months, p < 0.01) were significantly higher in the surveillance group. No significant difference was observed in secondary patency (hazard ratio: 0.83, p = 0.79). The total costs of AVG interventions were more than double in the surveillance group (110672 New Taiwan Dollar [NTD] vs. 51874 NTD, p < 0.01). Conclusions: Routine clinic surveillance in HD patients with AVGs and previous access complications resulted in significantly higher rates of graft-anastomosis stenting, PTA, and associated costs, without significant differences in AVA reconstruction rates or secondary patency. These results highlight the need for further assessment of the cost-effectiveness of routine AVG monitoring.

Safety and efficacy of an innovative external support device for de novo arterio-venous fistula creation: a French bicentric experience

BACKGROUND

The aim of this study was to evaluate the safety and efficacy of VasQTM, a permanent extravascular nitinol vascular support device, implanted around the anastomosis of de novo arteriovenous fistulas (AVF), in consecutive patients.

METHODS

This was a French prospective bicentric study. All patients with an indication for creation of a distal or proximal end to side AVF performed by supervised trainee were eligible. Follow-up was performed clinically and by Duplex scan at 6 weeks and 6 months post fistula creation. Primary endpoint was functional maturation at 6 weeks defined as successful use for dialysis via 2-needle cannulation in dialysis patients or a flow rate of ≥600 mL/min and a target vein diameter ≥6 mm for pre-dialysis patients. Overall functional success for dialysis patients was assessed as well.

RESULTS

Between March and November 2022, 21 patients received the VasQTM device and were followed for an average of 165 days. Median age was 61. Eleven patients (52%) were on dialysis at the time of implantation. AVFs were created with distal radial (N.=8), proximal radial (N.=5), brachial cephalic (N.=4) or brachial basilic (N.=4) arteries with 100% technical success . Functional maturation at 6-weeks was achieved in 81% (17/21). Functional success was 80% (12/15) with unassisted functional success of 67% (10/15) at 6 months for patients requiring dialysis at that time point. Two reoperations were performed within the device, one thrombectomy and one angioplasty, both were successful. Freedom from access-related interventions occurred in 71% (15/21) of the study population at 6-months.

CONCLUSIONS

This study demonstrates that the VasQTM AVFs achieved high rates of maturation at 6-weeks, without the need to modify standards of care. VasQTM can successfully assist in achieving excellent results at the introduction of the device to a new center.

Challenges surrounding hemodialysis initiation faced by undocumented immigrants

OBJECTIVE

Hemodialysis (HD) care in the United States for undocumented immigrants remains a challenging issue. The objective of this study is to evaluate the timeliness of nephrology and vascular surgery care provided to undocumented immigrants with end-stage renal disease compared with their documented counterparts. Additionally, we evaluate catheter-related complications in undocumented patients on HD.

METHODS

A retrospective chart analysis was performed of patients undergoing first-time arteriovenous access (AVA) creation at a single center from 2012 to 2018 to compare outcomes between documented and undocumented patients. Additionally, within the undocumented group, we compared outcomes between patients dependent on a central venous catheter (CVC group) to patients with a CVC and transition to an AVA (CAV group). The primary outcomes were time to initial evaluation by nephrology, vascular surgery, and AVA creation, as well as complications associated with long-term CVC use within the undocumented patients.

RESULTS

A total of 290 patients underwent first-time AVA creation (62 undocumented; 228 documented). Undocumented patients were younger at the time of surgery and, more commonly, Hispanic. Undocumented patients were more likely to receive their first nephrology evaluation upon HD initiation (59.7% vs 25.4%; P < .001). Regarding vascular access surgery initial evaluation for AVA creation, undocumented patients were more likely to be evaluated after initiating HD (74.2% vs 38.6%; P < .001). After being evaluated for AVA creation, there was no difference in time from vascular surgery evaluation to surgery (25 days vs 20 days; P = .95) or from surgery to AVA maturation (77 days vs 57 days; P = .31). As a result, undocumented patients were more likely to start dialysis with a CVC (90.3% vs 66.7%; P = .0004). Undocumented patients in the CVC group were more likely to experience catheter-related complications compared with their undocumented counterparts in the CAV group (CVC 72.5% vs CAV 45.9%; P = .032). The CAV patients were found to have an earlier occurrence of their first catheter-related complications, driving an earlier evaluation for AVA creation and subsequent CVC removal.

CONCLUSIONS

Due to limited access to health care, undocumented immigrants with end-stage renal disease had a significant delay in evaluation by nephrologists and vascular access surgeons for AVA creation with a higher use of CVC for dialysis initiation. CVC-related complications are highly frequent and avoidable in undocumented patients with an earlier referral for creation of appropriate AVA.

Cost-Effective Day Surgery for Arteriovenous Fistula Stenosis: A Viable Model for Hemodialysis Patients

BACKGROUND For patients with end-stage renal disease, arteriovenous fistulas (AVFs) are often used for hemodialysis, but stenosis can impair their function. Traditional inpatient procedures to address AVF stenosis are effective but resource-intensive, prompting the need for alternative approaches like day surgery to optimize care and reduce costs. This study evaluated the feasibility of a day surgery model for AVF stenosis treatment in maintenance hemodialysis (MHD) patients, aiming to develop a cost-effective and high-quality care model. MATERIAL AND METHODS A prospective cohort study was conducted with 186 MHD patients undergoing AVF stenosis intervention between July 2022 and May, 2023. Patients were divided into a day surgery group (n=112) and a ward group (n=74). Various preoperative, intraoperative, and postoperative parameters were recorded, including AVF patency, complications, and rehospitalization rates. Follow-up assessments were conducted on postoperative days 1, 3, 7, and 30, with long-term patency evaluated at 6 and 12 months. RESULTS The day surgery group achieved a technical success rate of 99.11% and a complication rate of 3.57%, compared to 97.30% and 1.35% in the ward group. The day surgery group also had significantly shorter waiting times for beds, shorter hospital stays, and lower hospitalization costs (P<0.01). No significant differences were found between the groups in preoperative or postoperative parameters. CONCLUSIONS The day surgery model for AVF stenosis intervention in MHD patients is a viable option, showing comparable success and complication rates to inpatient surgery while significantly reducing hospital stays and costs.

Global hemodialysis vascular access care: Three decades of evolution

The development of vascular access for hemodialysis has come a long way since 1943 when the first hemodialysis treatment was performed in humans by connecting an artery and vein using an external glass canula. Since then, vascular access care has evolved robustly through contributions from numerous countries and professional nephrology societies, worldwide. To understand the global distribution and contribution of different specialties to medical literature on dialysis vascular access care, we performed a literature search from 1991 to 2021 and identified 2768 articles from 74 countries. The majority of publications originated from the United States (41.5%), followed by China (5.1%) and the United Kingdom (4.6%). Our search results comprise of observational studies (43%), case reports/series (27%), review articles (16.5%) and clinical trials (12%). A large proportion of articles were published in Nephrology journals (49%), followed by General Medicine (14%), Surgery (10%), Vascular Medicine (8%), and Interventional Radiology journals (4%). With the introduction of interventional nephrology, nephrologists will be able to assume the majority of the responsibility for dialysis vascular access care and above all maintain a close interdisciplinary collaboration with other specialties to provide optimum patient care. In this review article, we discuss the history, evolving knowledge, challenges, educational opportunities, and future directions of dialysis vascular access care, worldwide.

The effect of early conversion from central venous catheter to arteriovenous fistula on hospitalization and mortality in incident haemodialysis patients

BACKGROUND

Controversy remains as to whether initiating haemodialysis (HD) with a central venous catheter (CVC) and vascular access conversion are associated with the risk of morbidity and mortality in incident HD patients.

METHODS

At our dialysis centre, the vascular access strategy is to create an arteriovenous fistula (AVF) early and use the AVF to initiate HD. In emergency situations, HD is initiated with a CVC and subsequent conversion from a CVC to an AVF as soon as possible. The effects of early AVF conversion on hospitalization and mortality were analysed.

RESULTS

At HD initiation, 35.42% used AVF, 15.63% used CVC with immature AVF and 48.96% used CVC, and all patients were able to convert from CVC to AVF within approximately 3 months. Compared to starting HD using an AVF, using a CVC was associated with access-related hospitalizations at 2 years, regardless of whether an AVF was created before (incidence rate ratio (IRR) = 3.02, 95% CI 0.89-10.24, p = 0.03) or after (IRR = 4.10, 95% CI 1.55-10.85, p < 0.01) HD initiation. The Kaplan-Meier method showed that the 2-year survival probability was not statistically significant between the three groups (log-rank χ2 = 0.165, p = 0.921). Multivariate Cox proportional hazards regression showed that starting HD with a CVC was not associated with mortality at 2 years (p > 0.05).

CONCLUSION

In this cohort, initiating HD with a CVC was associated with more access-related hospitalizations. Under the impact of an early AVF conversion strategy, despite initiating HD with a CVC, subsequent conversion from a CVC to an AVF within approximately 3 months had no impact on all-cause mortality in incident HD patients.

What are the reported procedural costs of vascular access surgery?

INTRODUCTION

Since the inception of arteriovenous grafts (AVG) as a novel technique, there has been greater emphasis on the assessment of outcomes rather than costs. Gross-costing methods over-simplify vascular access surgery and do not reflect the true costs of the service, preventing accurate cost-effectiveness analysis. The aim of this study is to assess the reporting of procedural costs of arteriovenous access creation in economic analyses of vascular access surgery, and to compare the reported costs of the two most performed procedures - arteriovenous fistula (AVF) and arteriovenous graft (AVG).

METHODS

This systematic review included studies reporting a per-procedure cost for AVF or AVG creation. Costs were adjusted from original to target price year using a Gross Domestic Product (GDP) deflator index and converted to 2021 US Dollars using conversion rates based on purchasing power parities.

RESULTS

The results demonstrate wide discrepancy in the reported procedural costs of arteriovenous access creation. Most of the data represents retrospectively observed costs rather than prospective data collected on an intention-to-treat basis. Charges are frequently presented in lieu of costs, and aggregated gross-costing methodology predominates rather than more accurate micro-costing.

CONCLUSION

Future micro-costing studies of vascular access surgery are essential to allow a greater understanding of cost-drivers and allow accurate cost-effectiveness analysis.

Is it possible to reach the catheter target proposed by the guidelines? Reasons for catheter use in prevalent hemodialysis patients

INTRODUCTION

Despite the recommendations of the clinical guidelines, the percentage of central venous catheters (CVC) continues to be above the recommended standards. We do not know whether the increasing use of catheters is due to unavoidable or avoidable factors and, in the latter case, it would be in our power to modify these results. The aim of this study was to analyze the causes that condition the use of CVC in a prevalent hemodialysis (HD) population in order to identify those modifiable factors on which to act in order to achieve the objectives of the guidelines.

METHODS

Retrospective, descriptive and observational study in all prevalent patients on chronic hemodialysis belonging to 7 hemodialysis centers in Madrid, Castilla-León and Galicia in a cross-sectional study carried out in June 2021 (637 patients). The following were analyzed: age, sex, nationality, etiology of CKD, the vascular access with which they started hemodialysis, the number of previous failed arteriovenous fistulas (AVF), time since the start of HD, time since the placement of the CVC for the first time, the situation with respect to surgery and the causes of being a CVC carrier. In patients whose cause was refusal to undergo AVF, patients were asked about the cause of the refusal by directed questioning.

RESULTS

Of the 637 patients studied, 255 (40%) had a CVC, 346 had an AVF (54.3%) and 36 (5.7%) had a prosthesis. Of the 255 patients with CVC, 20.4% (52 p) were awaiting vascular access (AVF/prosthesis), 10.2% (26 p) had an AVF but could not be used and 69.4% (177 p) were not considered candidates for surgery (due to vascular surgery (16.9%; 43 pac), nephrology (16.5%, 42 pac) and patient refusal (36%; 92 pac). The most frequent cause for refusal of AVF was fear and patient preference. One of the most important factors associated with CVC use in prevalent patients was having started hemodialysis with a CVC. The greatest use of CVC at the start of HD was significantly associated with having more than one AVF performed, or starting HD urgently and not having been followed up and evaluated in the ACKD consultation.

CONCLUSIONS

There is a high percentage of patients with a central venous catheter due to modifiable causes, which makes it necessary to systematically evaluate the process of creating AVF in order to enhance the planning, creation and maintenance of vascular access from the ACKD clinic, and to achieve the objective of the guidelines.

Outcomes of balloon-assisted maturation with large-diameter balloons

OBJECTIVES

Balloon-assisted maturation (BAM) is a well-established technique for maturation of inadequate arteriovenous fistulas (AVF). The objective of this study was to evaluate outcomes of initial BAM using large-diameter angioplasty balloons.

METHODS

Charts of patients who underwent BAM between 2018 and 2021 at a single academic institution were reviewed. AVF maturation rate was the primary outcome. Secondary outcomes included procedural complications, re-intervention rates, post-procedure vein diameter, and time to catheter-free hemodialysis (HD). Outcomes of patients that underwent initial BAM with ⩾7 mm diameter balloons (Group I) were compared to those of patients that had initial BAM with <7 mm balloons (Group II).

RESULTS

Group I (n = 149) was a significantly younger cohort and had more men compared to Group II (n = 90). There were no significant differences associated with procedural details and complication rates. Median vein diameter was larger (5.9 mm, IQR: 5-6.4) in Group I compared to Group II (5.1 mm, IQR: 4.2-5.9; p = 0.03) on post-procedure Duplex ultrasound. There was also a higher incidence of vein stenosis in Group II. The overall maturation rate was higher in Group I (97% vs 88%, p = 0.003), and a larger proportion of patients in Group II required more than one BAM to achieve maturation (33% vs 16%, p = 0.002). The median time to catheter-free HD after first BAM was 29 days (IQR: 19-47) in Group I and 42 days (IQR: 24-75) in Group II (p = 0.002). At 60 days after first BAM, the incidence of catheter-free HD was 83% in Group I versus 67% in Group II (p = 0.001).

CONCLUSIONS

Our study demonstrates that the ability to utilize large angioplasty balloons during initial BAM is associated with higher rates of AVF maturation with fewer re-interventions and shorter time to catheter-free dialysis. AVFs that can tolerate this procedure often have more favorable baseline characteristics.

Recurrent thrombosis and patency of the arteriovenous access in patients receiving hemodialysis

BACKGROUND

Thrombosis of the vascular access in patients with end-stage renal disease requiring hemodialysis are common and require timely interventional procedures to restore patency. The aim of the current study was to identify factors having a significant effect on patency rates after access thrombosis. Our hypothesis was the length of time between the initial clotting of the access and the subsequent percutaneous declotting impacts the patency rates of the vascular access.

METHODS

In this retrospective cohort study, patients with a clotted arteriovenous access between Jan 1, 2011, and Jan 1, 2016, were included. Demographics, access history, and associated details of the access procedure were reviewed from the electronic medical record. Statistical analysis was done using t-test and chi-square or fisher exact tests to compare arteriovenous fistulae (AVF) and arteriovenous grafts (AVG). Primary patency, defined as the time from index procedure to endpoint, was analyzed using the Kaplan-Meier method and log rank test.

RESULTS

There were 883 percutaneous declotting procedures reviewed. About 351 procedures were performed in patients with an AVF and 532 with an AVG. The mean time from thrombosis to declotting was 1.71 ± 2.29 days. The overall median primary patency for both AVF and AVG was 43 days with no difference in patency between patients with AVF (39 days) versus AVG (42 days; p = 0.385). The time period from access thrombosis to declotting did not affect patency rates for either AVG or AVF (p = 0.385). On multivariable analysis, prior intervention (HR: 1.32, 95% CI: 1.14-1.53, p < 0.001) and cardiovascular disease (HR: 1.19, 95% CI: 1.03-1.37, p = 0.016) were independently associated with access patency.

CONCLUSIONS

Time from thrombosis to declotting did not affect patency rates however once there was a thrombotic event, recurrent thrombosis requiring intervention was common with patency significantly decreased. Future prospective studies to validate our results and study pathogenic mechanisms of recurrent thrombosis are warranted.

A review of the current recommendations and practices for hemodialysis access monitoring and maintenance procedures

The growing number of prevalent arteriovenous (AV) accesses has been associated with an increase in the incidence of procedures being performed to maintain patency. To reduce the rate of unnecessary procedures, the 2019 Kidney Disease Outcome Quality Initiative guidelines addended the AV access surveillance recommendations, which includes clinical monitoring and assessment of dialysis adequacy alone. Abnormal clinical findings would necessitate follow-up angiography with or without confirmatory duplex ultrasound. Due to poor patency, increased surveillance schedules have been proposed to identify stenosis early and potentially prevent acute thrombotic events and AV access failure. In this review, we outlined current AV access monitoring and maintenance procedure recommendations, as described by the Centers for Medicare and Medicaid Services and 2019 Kidney Disease Outcome Quality Initiative guidelines. In addition, we highlight the findings of recently published randomized controlled trials that have examined increased surveillance schedules.

Transhepatic double lumen hemodialysis catheter in exhausted vascular access: Feasibility, functionality, and outcome among hemodialysis patients

INTRODUCTION

Permanent arteriovenous fistula and graft are considered the best options for hemodialysis in end-stage renal disease patients. Temporary access using the internal jugular or femoral veins is the feasible option in acute cases of dialysis and if permanent access is unavailable. Occasionally, however, these access sites are unusable after consecutive blockage of the upper and lower extremities veins. A transhepatic or translumbar approach might be the only unconventional way to ensure a sufficient blood flow for adequate dialysis.

METHOD

Retrospective data on all transhepatic catheters (THCs) in patients at the King Faisal Specialist Hospital and Research Center in Jeddah, Saudi Arabia were collected. The catheters were inserted over a 10-year period (2009-2019). A minimum of 1 year of follow-up from the last catheter insertion was considered for analysis.

RESULTS

A total of 12 patients had THCs with a mean age of 42.5 ± 12.2 and pre-insertion mean dialysis duration of 130.0 ± 72.9 months. All catheters were functional from the start with no immediate complications. A total of 35 catheter replacements over guidewires were made with a median of 2.0 catheters (range of 0-10). The mean blood flow was 300 ± 30 ml/minute with a mean Kt/v of 1.4 ± 0.4. The median initial (primary) device service interval was 68 (range 6-1531 days) and the median total access site service interval was 392 (range 76-2698 days). Catheter complications included catheter migration, thrombosis, and bloodstream infection occurring at a rate of 0.12, 0.18, and 0.046 per 100 catheter days respectively.

CONCLUSIONS

Transhepatic catheters provide safe, feasible access in patients with exhausted vascular access. Patients who undergo THC insertion should be worked up for innovative permanent vascular access or urgent transplantation utilizing unconventional vascular techniques to avoid death due to lack of access.

Exploring kidney dialysis costs in the United States: a scoping review

AIMS

The increasing prevalence of end-stage renal disease (ESRD) in the United States (US) represents a considerable economic burden due to the high cost of dialysis treatment. This review examines data from real-world studies to identify cost drivers and explore areas where dialysis costs could be reduced.

METHODS

We identified and synthesized evidence published from 2016-2023 reporting direct dialysis costs in adult US patients from a comprehensive literature search of MEDLINE, Embase, and grey literature sources (e.g. US Renal Data System reports).

RESULTS

Most identified data related to Medicare expenditures. Overall Medicare spending in 2020 was $29B for hemodialysis and $2.8B for peritoneal dialysis (PD). Dialysis costs accounted for almost 80% of total Medicare expenditures on ESRD beneficiaries. Private insurance payers consistently pay more for dialysis; for example, per person per month spending by private insurers on outpatient dialysis was estimated at $10,149 compared with Medicare spending of $3,364. Dialysis costs were higher in specific high-risk patient groups (e.g. type 2 diabetes, hepatitis C). Spending on hemodialysis was higher than on PD, but the gap in spending between PD and hemodialysis is closing. Vascular access costs accounted for a substantial proportion of dialysis costs.

LIMITATIONS

Insufficient detail in the identified studies, especially related to outpatient costs, limits opportunities to identify key drivers. Differences between the studies in methods of measuring dialysis costs make generalization of these results difficult.

CONCLUSIONS

These findings indicate that prevention of or delay in progression to ESRD could have considerable cost savings for Medicare and private payers, particularly in patients with high-risk conditions such as type 2 diabetes. More efficient use of resources is needed, including low-cost medication, to improve clinical outcomes and lower overall costs, especially in high-risk groups. Widening access to PD where it is safe and appropriate may help to reduce dialysis costs.

Is there a role of the kidney failure risk equation in optimizing timing of vascular access creation in pre-dialysis patients?

BACKGROUND

The aims of this study were to assess the utility of using the Kidney Failure Risk Equation (KFRE) as an indicator to guide timing of vascular access creation in pre-dialysis patients.

MATERIALS AND METHODS

Patients referred for vascular access creation had KFRE calculated at the time of assessment and compared to standard criteria for referral. Receiver operating characteristic curves were produced for each parameter. The outcomes at 3 months, 6 months, and 1 year were used as time points for analysis.

RESULTS

Two hundred and three patients were assessed, and full data sets were available on 190 (94.6%). Access was created in 156 patients (82.1%) with a fistula in 153 (98.7%). Only 65.7% initiated dialysis within the follow up period. Those patients with an AV access created (n = 156) 37 (23.7%) did not reach end stage over the entire follow up period. Of the remaining patients (n = 119) that reached end stage 72.2% (n = 86) started on an AVF/AVG and 27.7% (n = 33) on a CVC. Using ROC analysis for referral eGFR, ACR and KFRE predicting dialysis initiation predictors resulted in C statistics for eGFR, ACR, and KFRE2 of 0.68 (0.58-0.79), 0.75 (0.65-0.84), and 0.72 (0.62-0.81) at 3 months; 0.73 (0.65-0.81), 0.70 (0.62-0.78), and 0.75 (0.67-0.81) at 6 months; and 0.65 (0.57-0.72); 0.67 (0.59-0.75), and 0.68 (0.61-0.77) at 12 months.

CONCLUSIONS

In a group of patients referred for vascular access creation the predictive models are relatively poor when applied to initiation of dialysis. The application of current guidelines to fistula creation appears to result in a high rate of unnecessary fistula formation and non-use. The study requires further evaluation in a test set of patients to confirm these findings and also identify where such risk based approaches may need modification.

The outcomes of a novel two-stage proximal brachial artery to proximal basilic/brachial vein arteriovenous graft extension for dialysis access

BACKGROUND

We describe a technique to mature a basilic/brachial vein in the mid-arm in preparation for a second stage loop proximal brachial artery to basilic/brachial vein arteriovenous graft (BBAVG). This can occur after a failed basilic/brachial vein transposition or a lack of adequate veins in the distal arm. This allows a mature vein to be used in an end-to-end configuration as an outflow to a BBAVG while preserving proximal vessels for the future.

METHODS

This single-center retrospective study was performed from 2015 to 2021, including 104 AVG patients divided into three groups: (1) Patients who failed a basilic vein transposition and had an enlarged vein suitable for an AVG outflow; (2) Patients who had a small caliber basilic/brachial vein after the transposition, requiring a mid-arm brachial artery to brachial/basilic arteriovenous fistula (AVF) creation with a subsequent AVG extension; (3) and lastly, patients who had no distal arm veins available and required a primary brachial artery to basilic/brachial AVF with AVG extension. A survival analysis was performed looking at time to loss of primary and secondary patency, calculated with Kaplan-Meier estimates and Cox regression models adjusted for covariates.

RESULTS

The median follow-up time was 11 months (IQ = 11-30 months). The survival analysis showed 28% lost primary patency at a median time of 9 months, and 14% lost secondary patency at a median time of 61 months. Overall secondary patency of the vascular access measured at 12 months was 85.6%. Loss of primary (p = 0.008) and secondary patency (p = 0.017), as well as patency during the first 12 months (p = 0.036), were all significantly associated with increased age when adjusting for covariates.

CONCLUSIONS

Our results suggest that the graft extension technique using a mature vein from a previous fistula can result in reliable and durable access. This is important for patients with limited access for hemodialysis, as the axillary vein is preserved for future use if needed.

Early Follow-Up after Arteriovenous Fistula Creation is Associated with Improved Access-Related Outcomes

BACKGROUND

Up to 60% of arteriovenous fistulas (AVF) require intervention to assist maturation, which prolongs the time until it can be used for hemodialysis (HD). Current guidelines recommend early postoperative AVF examination to detect and address immaturity to decrease time to maturation. This study evaluates how the timing of postoperative follow-up to assess AVF maturity affects patients' outcomes.

METHODS

All patients who underwent AVF creation between 2017 and 2021 in an academic medical center were retrospectively reviewed, excluding patients lost to follow-up or not on HD. Outcomes were compared between patients that had delayed follow-up to assess AVF maturity, >8 weeks post surgery, versus early follow-up, <8 weeks post-surgery. AVF evaluation for maturity consisted of physical examination and duplex ultrasound. Primary endpoints were time to first cannulation (interval from AVF creation to first successful cannulation) and time to catheter-free dialysis (interval from AVF creation to central venous catheter removal).

RESULTS

A total of 400 patients were identified: 111 in the delayed follow-up group and 289 in the early follow-up group. The median time to follow-up was 78 days (interquartile range [IQR], 66-125) in the delayed follow-up group versus 39 days (IQR, 36-47) in the early follow-up group, (P < 0.0001). The maturation rate was 87% in the delayed follow-up group versus 81% in the early follow-up group, (P = 0.1) and both groups had similar rates of interventions to assist maturation (66% vs. 57%, P = 0.2). The early follow-up group had a significantly shorter median time to first cannulation (50 vs. 88 days; P < 0.0001) and shorter time to catheter-free HD (75 vs. 118 days; P <0.0001). At 4 months after AVF creation, the incidence of first cannulation was 74% in the early follow-up group versus 63% in the delayed follow-up group (P = 0.001). Similarly, the incidence of catheter-free dialysis was 65% in the early follow-up group versus 50% in the delayed follow-up group at 4 months postoperatively, (P = 0.036).

CONCLUSIONS

Early postoperative follow-up for evaluation of fistula maturation is associated with reduced time to first successful cannulation of AVF for HD and reduced time to catheter-free dialysis.

Effects of a More Selective Arteriovenous Fistula Strategy on Vascular Access Outcomes

SIGNIFICANCE STATEMENT

The optimal choice of vascular access for patients undergoing hemodialysis-arteriovenous fistula (AVF) or arteriovenous graft (AVG)-remains controversial. In a pragmatic observational study of 692 patients, the authors found that among patients who initiated hemodialysis with a central vein catheter (CVC), a strategy that maximized AVF placement resulted in a higher frequency of access procedures and greater access management costs for patients who initially received an AVF than an AVG. A more selective policy that avoided AVF placement if an AVF was predicted to be at high risk of failure resulted in a lower frequency of access procedures and access costs in patients receiving an AVF versus an AVG. These findings suggest that clinicians should be more selective in placing AVFs because this approach improves vascular access outcomes.

BACKGROUND

The optimal choice of initial vascular access-arteriovenous fistula (AVF) or graft (AVG)-remains controversial, particularly in patients initiating hemodialysis with a central venous catheter (CVC).

METHODS

In a pragmatic observational study of patients who initiated hemodialysis with a CVC and subsequently received an AVF or AVG, we compared a less selective vascular access strategy of maximizing AVF creation (period 1; 408 patients in 2004 through 2012) with a more selective policy of avoiding AVF creation if failure was likely (period 2; 284 patients in 2013 through 2019). Prespecified end points included frequency of vascular access procedures, access management costs, and duration of catheter dependence. We also compared access outcomes in all patients with an initial AVF or AVG in the two periods.

RESULTS

An initial AVG placement was significantly more common in period 2 (41%) versus period 1 (28%). Frequency of all access procedures per 100 patient-years was significantly higher in patients with an initial AVF than an AVG in period 1 and lower in period 2. Median annual access management costs were significantly higher among patients with AVF ($10,642) versus patients with AVG ($6810) in period 1 but significantly lower in period 2 ($5481 versus $8253, respectively). Years of catheter dependence per 100 patient-years was three-fold higher in patients with AVF versus patients with AVG in period 1 (23.3 versus 8.1, respectively), but only 30% higher in period 2 (20.8 versus 16.0, respectively). When all patients were aggregated, the median annual access management cost was significantly lower in period 2 ($6757) than in period 1 ($9781).

CONCLUSIONS

A more selective approach to AVF placement reduces frequency of vascular access procedures and cost of access management.

Impact of preoperative exercise in not initially candidates to native arteriovenous fistulas

BACKGROUND

Native autologous arteriovenous fistula (AVFn) is the preferred vascular access for hemodialysis due to its long term patency and low complication rate. A challenging limitation is the anatomical inability to perform AVFn and failure of maturation. Preoperative isometric exercise (PIE) can increase vascular calibers and improve the rate of distal AVF. However, it is unknown whether PIE might enhance the performance of AVFn in patients who are not initially candidates.

METHODS

A retrospective observational study was conducted over a population of 45 patients evaluated in vascular access clinic, 23 were not initially candidates for radiocephalic (NRC-AVF) and 22 were not candidates for autologous fistula at all (NA-AVF). They were assigned to perform PIE with handgrip device and revaluated.

RESULTS

After 4-8 weeks of PIE, a AVFn was performed in 16 patients from NA-AVF group and a radiocephalic AVFn was performed in 21 patients from NRC-AVF group. Both groups experienced a significant and similar increase in venous caliber 0.91 ± 0.43 mm in NA-AVF versus 0.76 ± 0.47 mm in NRC-AVF (p = 0.336) and arterial caliber 0.18 ± 0.24 mm versus 0.18 ± 0.21 mm (p = 0.928), respectively. Nevertheless, primary failure rate was significantly higher in NA-AVF (n = 8, 50%) than in NRC-AVF group (n = 3, 14.3%) (p = 0.030). After 6 months, the fistula usability for dialysis was only 50% in NA-AVF, while 86.7% were dialyzed by fistula in NRC-AVF group (p = 0.038).

CONCLUSIONS

PIE allowed the allocation of an AVFn in patients not initially candidates, but entailed a high rate of maturation failure. Patients not candidates to radiocephalic AVF benefited from PIE and preserved a long term usability of AVF for dialysis.

A systematic review aggregated data and individual participant data meta-analysis of percutaneous endovascular arteriovenous fistula

OBJECTIVE

To assess the short-term and mid-term safety and efficacy of percutaneous endovascular arteriovenous fistula (pAVF) creation.

METHODS

A systematic search was implemented corresponding to the PRISMA 2020 and the PRISMA for individual participant data (IPD) systematic reviews 2015. Aggregated data from the included studies were obtained and meta-analyzed regarding both the overall pAVF efficacy and the comparison of pAVF with surgical AVF (sAVF). We performed a two-stage IPD meta-analysis for studies comparing pAVF and sAVF regarding primary and secondary patency. Primary end points included primary patency, secondary patency, and functional cannulation.

RESULTS

Eighteen studies with 1863 patients were included. The overall pAVF, primary patency, secondary patency, functional cannulation and abandonment rates were 54.01% (95% confidence interval [CI], 40.69-66.79), 87.27% (95% CI, 81.53-91.42), 79.94% (95% CI, 65.94-89.13), and 15.58% (95% CI, 7.77-28.79), respectively. The overall pAVF, technical success, maturation, reintervention per person-years and mean time to maturation rates were 97.08% (95% CI, 95.66-98.04), 82.13% (95% CI, 71.64-89.32), 0.80 (95% CI, 0.34-1.47), and 58 days (95% CI, 36.64-92.82), respectively. Secondary patency and pAVF abandonment rates where the only end points were WavelinQ and Ellipsys displayed statistically significant differences of 81.36% (95% CI, 76.15-85.65) versus 92.12% (95% CI, 87.94-94.93) and 32.54% (95% CI, 22.23-44.87) versus 11.13% (95% CI, 4.82-23.65). An IPD meta-analysis of hazard ratios for primary and secondary patency between pAVF and sAVF were 1.27 (95% CI, 0.61-2.67) and 1.25 (95% CI, 0.87-1.80), favoring sAVF. Statistically significant difference between pAVF and sAVF were solely depicted for steal syndrome relative risk of 5.91 (95% CI, 1.12-31.12) and wound infections relative risk of 4.19 (95% CI, 1.04-16.88). Plotting of pAVF smoothed hazard estimate displayed an upsurge in the probability of primary patency failure at 1 month after the intervention.

CONCLUSIONS

Although we failed to identify statistically significant differences between pAVF and sAVF regarding any of the primary end points, pAVF displayed a decreased risk for steal syndrome and wound infection. Although both the Ellipsys and WavelinQ devices displayed satisfactory secondary patency rates, Ellipsys demonstrated a statistically significant improved rate compared with WavelinQ. Additionally, and despite the borderline statistically insignificant inferior reintervention rate displayed by WavelinQ, one in three WavelinQ pAVFs resulted in abandonment. The introduction of pAVF as a treatment modality calls for standardized definition adjustment and improvement.

Lessons learnt and future directions in managing dialysis access during the COVID 19 pandemic: Patient and provider experience in the United States

BACKGROUND

The COVID 19 pandemic adversely impacted delivery of preventive, routine, urgent, and essential care worldwide. Dialysis access care was particularly affected due to the lack of specific guidelines regarding procedures for its creation and maintenance. Early guidance by Centers for Medicare and Medicaid was inadvertently interpreted as guidance to stop dialysis access procedures. Prompt action by professional societies was needed to furnish detailed guidance to establish essential nature of these procedures.

METHODS

The American Society of Diagnostic and Interventional Nephrology (ASDIN) issued a joint statement with Vascular Access Society of the Americas (VASA) - "Maintaining Lifelines for ESKD Patients" to clearly establish the role of vascular access as a lifeline for ESKD (End Stage Kidney Disease) patients and the importance and urgency of its timely management. ASDIN also conducted a survey in mid-2020, that was administered to the ASDIN database as well as shared with the general public via the organization's social media platforms. The respondents reported their experiences in the care of dialysis access, practice patterns and the utility of the ASDIN-VASA statement during the COVID 19 pandemic.

RESULTS

Of the 2030 individual surveys sent, 581 were opened and 53 (9.1%) responses were received from different parts of the country and from different practice settings. ASDIN COVID 19 triage document was frequently utilized and 83% of respondents found the document valuable. The survey also revealed multiple obstacles, including logistical and financial issues that led to significant disruption of services.

CONCLUSIONS

The care of dialysis access was significantly affected in the United States during the COVID 19 pandemic due to multiple reasons. ASDIN actions provided valuable specific guidance regarding and explored barriers to dialysis access care. We describe those results and discuss strategies to prevent COVID 19 transmission with innovative strategies of providing access care. Individualized decision making is of essence when considering dialysis access procedures.

Pre-emptive or reactive treatment, angioplasty or stent-graft? The outcome for interventions for venous stenosis in early-cannulation arteriovenous grafts

BACKGROUND

Early-cannulation arteriovenous grafts (ecAVG) have good initial patency, but frequent episodes of reintervention for venous stenosis (VS) and thrombosis limit their use. Stent grafts (SG) have shown promise in reducing re-interventions and improving functional patency for dysfunctional ecAVG and recurrent VS. There is little data on the impact of stent grafts as the first elective procedure for VS. The aim of this study was to determine firstly, if treating VS whilst asymptomatic has a better outcome than treating after presentation with thrombosis; and secondly, to determine the best initial treatment for asymptomatic VS: SG or angioplasty.

METHODS

A retrospective study was performed of 259 ecAVG with a sutured anastomosis. The case-mix and outcomes of 153 who presented with VS was analysed by presentation (elective at surveillance or emergency following thrombosis), and then for only elective patients, by treatment (SG vs angioplasty).

RESULTS

There was no significant difference in case-mix and time to presentation by mode of presentation (100 elective and 53 with thrombosis) other than a higher rate of pro-thrombotic disorders in thrombosed ecAVG. Thrombosed ecAVG had poorer outcomes with increased re-intervention rates and thrombosis in the following year, and reduced long-term functional patency. In patients presenting electively, primary SG rather than angioplasty led to significantly reduced thrombosis rates, a longer time to re-intervention in the following year, and superior long-term functional patency. The use of SG was the same in both groups. Both the mode of presentation and the type of intervention performed were independently predictive of a poorer subsequent functional patency.

CONCLUSIONS

Primary elective stent-grafting may be the optimal strategy to reducing maintenance costs with ecAVG.

Placing an appropriate tunneled dialysis catheter in an appropriate patient including the nonconventional sites

Hemodialysis remains the most frequently chosen kidney replacement modality across the world. A well-functioning dialysis vascular access is critical to providing successful dialysis therapy. Despite its drawbacks, central venous catheter is commonly used as a vascular access to initiate hemodialysis therapy in acute and chronic settings. The growing recognition of providing patient centric care and per recommendations from the recently published Kidney Disease Outcome Quality Initiative (KDOQI) Vascular Access Guidelines, selecting the appropriate patient population for a central venous catheter placement involves implementing the End Stage Kidney Disease (ESKD) Life-Plan strategy. The current review examines the circumstances and challenges that increasingly lead to the hemodialysis catheter being the default and the only available choice for patients. The current review outlines the clinical scenarios for selecting an appropriate patient for hemodialysis catheter use for short-term or long-term needs. The review further discusses clinical pointers to assist with the decision-making process on estimation on prospective catheter length selection, particularly in the intensive care unit setting without the aid of conventional fluoroscopic guidance. A hierarchy of conventional and non-conventional access sites is proposed based on KDOQI guidance and multi-disciplinary author experience. Non-conventional sites are reviewed, including complications and technical guidance, for trans-lumbar IVC, trans-hepatic, trans-renal, and other exotic sites.

Study protocol of a randomized controlled trial of fistula vs. graft arteriovenous vascular access in older adults with end-stage kidney disease on hemodialysis: the AV access trial

BACKGROUND

Treatment of end-stage kidney disease (ESKD) with hemodialysis requires surgical creation of an arteriovenous (AV) vascular access-fistula (AVF) or graft (AVG)-to avoid (or limit) the use of a central venous catheter (CVC). AVFs have long been considered the first-line vascular access option, with AVGs as second best. Recent studies have suggested that, in older adults, AVGs may be a better strategy than AVFs. Lacking evidence from well-powered randomized clinical trials, integration of these results into clinical decision making is challenging. The main objective of the AV Access Study is to compare, between the two types of AV access, clinical outcomes that are important to patients, physicians, and policy makers.

METHODS

This is a prospective, multicenter, randomized controlled trial in adults ≥ 60 years old receiving chronic hemodialysis via a CVC. Eligible participants must have co-existing cardiovascular disease, peripheral arterial disease, and/or diabetes mellitus; and vascular anatomy suitable for placement of either type of AV access. Participants are randomized, in a 1:1 ratio, to a strategy of AVG or AVF creation. An estimated 262 participants will be recruited across 7 healthcare systems, with average follow-up of 2 years. Questionnaires will be administered at baseline and semi-annually. The primary outcome is the rate of CVC-free days per 100 patient-days. The primary safety outcome is the cumulative incidence of vascular access (CVC or AV access)-related severe infections-defined as access infections that lead to hospitalization or death. Secondary outcomes include access-related healthcare costs and patients' experiences with vascular access care between the two treatment groups.

DISCUSSION

In the absence of studies using robust and unbiased research methodology to address vascular access care for hemodialysis patients, clinical decisions are limited to inferences from observational studies. The goal of the AV Access Study is to generate evidence to optimize vascular access care, based on objective, age-specific criteria, while incorporating goals of care and patient preference for vascular access type in clinical decision-making.

TRIAL REGISTRATION

This study is being conducted in accordance with the tenets of the Helsinki Declaration, and has been approved by the central institutional review board (IRB) of Wake Forest University Health Sciences (approval number: 00069593) and local IRB of each participating clinical center; and was registered on Nov 27, 2020, at ClinicalTrials.gov (NCT04646226).

Role of Antiplatelet Therapy in Hemodialysis Arteriovenous Graft Secondary Patency Following Successful Percutaneous Thrombectomy

PURPOSE

The purpose of this study was to elicit the relationship of antiplatelet therapy (AP) in maintaining arteriovenous graft (AVG) patency after successful percutaneous pharmacomechanical thrombectomy ("declot").

MATERIALS AND METHODS

This was an institutional review board-approved retrospective review of AVG declot procedures between July 2019 and August 2020. AVG characteristics, bleeding complications, anticoagulation and antiplatelet medication regimens, and thrombosis free survival were evaluated. Recurrent time-to-event analysis was performed using a Prentice-Williams-Peterson Gap time model was performed to evaluate AVG thrombosis free survival.

RESULTS

A total of 109 declots were technically successful and performed in 63 individual patients. The majority of procedures were performed in upper arm grafts (71%, n = 45). Dual antiplatelet (DAPT) was prescribed after 52 declots (48%), single antiplatelet was prescribed after 36 declots (33%), and anticoagulation was prescribed after 31 declots (28%). Median thrombosis free survival was 37 days (range 1-412 days) in the no antiplatelet group, 84 days (range 1-427 days) in the single antiplatelet group, and 93 days (range 3-407 days) in the DAPT group. Anti-platelet medications trended towards protective of AVG thrombosis in multivariate analysis (hazard ratio 0.84, 95% confidence interval 0.60-1.19); however, this did not reach statistical significance (P = 0.33). A total of 4 major and 5 minor bleeding events occurred.

CONCLUSION

The results of this study support further evaluation of AP therapy in preventing secondary rethrombosis of dialysis AVG.

Prevalence of Central Venous Stenosis among Black and White ESKD Patients with Dysfunctional Dialysis Access

In the United States, significant racial and ethnic disparities exist in chronic kidney disease (CKD) and its management. Hemodialysis constitutes the main stay of renal replacement therapy for end-stage kidney disease (ESKD), which is initiated using central venous catheters (CVC) in most CKD patients in the United States. Black ESKD patients have higher usage and greater time on CVC for hemodialysis compared to White patients. This trend places Black patients at a potentially higher risk for CVC-related complications such as central venous stenosis (CVS). We posited that Black patients would have a higher prevalence and a greater risk of CVS. A retrospective review was performed of ESKD patients who underwent a fistulogram for dialysis access malfunction. CVS was defined as > 50% stenosis in the central veins. Fistulograms of 428 ESKD patients were adjudicated, and CVS was noted in 167 of these patients. Of the entire cohort, 370 fistulograms belonged to self-reported unique Black and White ESKD patients, of whom 137 patients were noted to have CVS. There was no difference in the of CVS between Black (40%) and White (41%) ESKD patients. However, a higher severity of stenosis (>70%) (P = 0.03) was noted in White ESKD patients. An unadjusted model showed a significant association between CVS and cardiovascular disease and the use of CVCs. The risk-adjusted model showed a significant association between diabetes and CVS. Unlike arterial stenotic lesions, this work for the first time demonstrated higher prevalence of severe venous stenotic lesions in White ESKD patients and linked diabetes to stenotic venous disease. This work paves the way for future studies investigating the risk and influence of race and ethnicity on CVS using a larger and diverse data set.

Health insurance provider and endovascular treatment availability are associated with different hemodialysis vascular access profiles: A Brazilian national survey

In Brazil, most hemodialysis (HD) patients are treated by the country's public health system. However, accessibility to healthcare is different for public and private patients. This study aimed to identify the profile of vascular access in a Brazilian HD sample. Additionally, it aimed to examine the influence of public and private health insurance, accessibility to endovascular treatments, and timely arteriovenous access creation on the prevalence of tunneled catheters (TCs), non-tunneled catheters (NTCs), and arteriovenous (AV) access. We conducted a cross-sectional electronic survey across 834 centers. Centers were inquired about the number of patients with public and private health insurance, the profiles of vascular access, time for AV access creation, accessibility to TC insertion and endovascular treatments, and the availability of peritoneal dialysis and kidney transplantation. Logistic regression and multilevel logistic regression were performed to evaluate possible interactions between the independent variables. A total of 7,973 patients across 47 HD centers were included in the survey. Public health patients accounted for 77% of the study sample. The overall vascular access profiles of the public and private insurance groups were significantly different (p < 0.001). For patients with public health insurance, the prevalence of any catheter was 25%, while that for private patients was 31.8% (p < 0.001). The prevalence of TCs was more common in private patients (15.3% vs. 23.1%, p < 0.001). AV accesses were more common in public health patients (75% vs. 68.2%, p < 0.001), as were fistulas (72.4% vs. 63.1%, p < 0.001). AV grafts were more prevalent among patients with private insurance (2.6 vs. 5.1%, p < 0.001). The availability of endovascular treatments increased the chance of having a TC by 2.3-fold (OR = 2.33, 95% CI = 1.30-4.18); however, it did not reduce the chance of having any catheter. A high chance of having a catheter was found when the time to AV access creation exceeded 60 days. The differences between public and private patients may be explained by underpayments and the decreased accessibility to care infrastructure in the public system, especially for endovascular treatments. In this sample, public health patients had a decreased risk of having a TC over an NTC. Differences in care accessibility and insurance type might influence the type of vascular access.

Economics of drug-coated balloons for arteriovenous fistula stenosis in Japan and Korea based on the IN.PACT AV access trial

AIM

The recent IN.PACT AV Access study found drug-coated balloon therapy to be associated with reduced reinterventions compared to percutaneous transluminal angioplasty using standard balloons in the management of arteriovenous fistula stenosis. The economic implications of drug-coated balloon use in Asia, including Japan and Korea, remain unknown.

METHODS

A decision-analytic model was developed to calculate strategy-specific costs for Korea and Japan through 5-year follow-up. The analysis assumed maintained therapy benefit beyond current trial follow-up of 1 year in the base case, with several alternative scenarios explored in sensitivity analysis. Costs were derived from claims and reimbursement data, and projections were evaluated at 3 and 5 years post-index procedure.

RESULTS

Model-projected access circuit reintervention events for drug-coated versus standard balloons were 1.70 versus 2.76 (-1.06) and 2.53 versus 4.10 (-1.57) at 3 and 5 years in the base case. Corresponding 3- and 5-year costs were ₩6 211 103 versus ₩7 605 553 (-₩1 394 451) and ₩7 766 051 versus ₩10 124 954 (-₩2 358 904) in Korea, and ¥1 469 824 versus ¥1 504 161 (-¥34 337) and ¥1 956 931 versus ¥2 106 632 (-¥149 701) in Japan. In scenario analyses, drug-coated balloons remained cost saving at 3- and 5-year follow-up in Korea, but required up to 5 years to reach cost-savings in Japan. Drug-coated balloon use in reinterventions increased projected savings, as did younger treatment age.

CONCLUSION

Treatment of arteriovenous fistulas with the IN.PACT AV drug-coated balloon, based on preliminary data, may lead to meaningful reductions in reintervention costs that would render it cost-saving at timeframes of around 1 year in Korea and between 3 and 5 years in Japan.

Localized Perivascular Therapeutic Approaches to Inhibit Venous Neointimal Hyperplasia in Arteriovenous Fistula Access for Hemodialysis Use

An arteriovenous fistula (AVF) is the preferred vascular access for chronic hemodialysis, but high failure rates restrict its use. Optimizing patients' perioperative status and the surgical technique, among other methods for preventing primary AVF failure, continue to fall short in lowering failure rates in clinical practice. One of the predominant causes of AVF failure is neointimal hyperplasia (NIH), a process that results from the synergistic effects of inflammation, hypoxia, and hemodynamic shear stress on vascular tissue. Although several systemic therapies have aimed at suppressing NIH, none has shown a clear benefit towards this goal. Localized therapeutic approaches may improve rates of AVF maturation by providing direct structural and functional support to the maturating fistula, as well as by delivering higher doses of pharmacologic agents while avoiding the adverse effects associated with systemic administration of therapeutic agents. Novel materials-such as polymeric scaffolds and nanoparticles-have enabled the development of different perivascular therapies, such as supportive mechanical devices, targeted drug delivery, and cell-based therapeutics. In this review, we summarize various perivascular therapeutic approaches, available data on their effectiveness, and the outlook for localized therapies targeting NIH in the setting of AVF for hemodialysis use. Highlights: Most systemic therapies do not improve AVF patency outcomes; therefore, localized therapeutic approaches may be beneficial. Locally delivered drugs and medical devices may improve AVF patency outcomes by providing biological and mechanical support. Cell-based therapies have shown promise in suppressing NIH by delivering a more extensive array of bioactive substances in response to the biochemical changes in the AVF microenvironment.

Is there sex disparity in vascular access at dialysis initiation in France? A mediation analysis using the data of the REIN registry

Background

This study was conducted to estimate the direct effect of sex on the proportion of hemodialysis catheters at dialysis initiation and to investigate whether predialysis care or socioeconomic status acted as a mediator of the sex effect.

Methods

Patients who started dialysis between 01–01-2017 and 30–06-2018 in France were included using the data of the REIN registry. Logistic regression was performed to study the association between sex and the proportion of HD catheters. A mediation analysis with a counterfactual approach was carried out to evaluate whether there was an indirect effect of gender through the proxies of predialysis care (hemoglobin, albumin levels, glomerular filtration rate (GFR) at dialysis initiation) and socioeconomic status. Due to the identification of an interaction between gender and social deprivation, a subgroup analysis was performed among deprived and nondeprived patients.

Results

There were 16 032 patients included, and the sex ratio (M/F) was 10 405/5627. In the multivariable analysis, women were associated with a greater risk of starting dialysis with a catheter (OR 1.32 [95% CI: 1.23–1.42]). There was an indirect effect of sex on the proportion of HD catheters through proxies for predialysis care (albuminemia &lt; 30 g/L (OR 1.08 [95% CI: 1.05–1.10]), hemoglobin &lt; 11 g/dL (OR 1.03 [95% CI: 1.02–1.04]), GFR &lt; 7 ml/min (OR 1.05 [95% CI: 1.04–1.07])). Among deprived patients, there was no direct effect of sex on the catheter proportion.

Conclusions

Women were associated with a higher risk of starting dialysis through an HD catheter. The effect of sex was mediated by predialysis care, particularly for deprived patients.

Impact of the COVID pandemic on vascular access creation for hemodialysis in 16 Spanish hemodialysis centers

Background

The coronavirus disease (COVID) pandemic has resulted in a major disruption in healthcare that has affected several medical and surgical specialties. European and American Vascular Societies have proposed deferring the creation of an elective vascular access (VA) [autologous or prosthetic arteriovenous fistula (AVF) or arteriovenous graft (AVG)] in incident patients on haemodialysis (HD) in the era of the COVID pandemic. The aim of this study is to examine the impact of the COVID pandemic on VA creation and the central venous catheter (CVC)-related hospitalizations and complications in HD patients dialyzed in 16 Spanish HD units of three different regions.

Methods

We compared retrospectively two periods of time: the pre-COVID (1 January 2019–11 March 2020) and the COVID era (12 March 2020–30 June 2021) in all HD patients (prevalent and incident) dialyzed in our 16 HD centres. The variables analysed were type of VA (CVC, AVF and AVG) created, percentage of CVC in incident and prevalent HD patients, CVC-related hospitalizations and complications (infection, extrusion, disfunction, catheter removal) and percentage of CVC HD sessions that did not reach the goal of Kt (>45) as a marker of HD adequacy.

Results

A total of 1791 VAs for HD were created and 905 patients started HD during the study period. Patients who underwent vascular access surgery during the COVID period compared with pre-COVID period were significantly younger, with a significant decrease in surgical activity to create AVFs and AVGs in older HD patients (>75 and >85 years of age). There was a significant increase in CVC placement (from 59.7% to 69.5%; P < 0.001) from the pre-COVID to the COVID period. During the COVID pandemic, a significantly higher number of patients started HD through a CVC (80.3% versus 69.1%; P < 0.001). The percentage of CVC in prevalent HD patients has not decreased in the 19 months since the start of the pandemic [414 CVC/1058 prevalent patients (39.4%)]. No significant changes were detected in CVC-related hospitalizations between the pre-COVID and COVID periods. In the COVID period, a significant increase in catheter replacement and the percentage of HD session that did not reach the HD dose objective (Kt > 45) was observed.

Conclusions

COVID has presented a public health system crisis that has influenced VA for HD, with an increase in CVCs relative to AVFs. A decrease in HD sessions that did not reach the HD dose objective was observed in the COVID period compared with a pre-COVID period.

Interdisciplinary Care and Preparedness for Kidney Failure Management in a High-Risk Population

Rationale & Objective

Interdisciplinary care may improve health outcomes in patients with chronic kidney disease (CKD). Few studies have evaluated this model of health care delivery in racial and ethnic minorities.

Study Design

Retrospective cohort study.

Setting & Participants

Incident end-stage kidney disease (ESKD) patients at Montefiore Medical Center from October 1, 2013, to October 31, 2019.

Exposure

Pre-ESKD interdisciplinary care.

Outcomes

Pre-ESKD transplant listing and optimal kidney replacement therapy (KRT) start (use of arteriovenous access at hemodialysis initiation, outpatient hemodialysis start, preemptive transplant, or peritoneal dialysis as the first modality).

Analytical Approach

We constructed multivariable logistic regression models adjusted for sociodemographic and clinical factors to determine the odds of transplant listing and optimal KRT start between interdisciplinary versus the usual care group.

Results

Of the 295 incident ESKD patients included in our study, 84 received interdisciplinary care and 211 received usual nephrology care. The mean age was 59.9 years (standard deviation, 13.9 years), 47% were women, and 87% were African American or Hispanic. Baseline characteristics were similar between the groups, except that the interdisciplinary care group had a lower prevalence of hypertension (60% vs 75%). Compared with usual care, a higher proportion of patients in the interdisciplinary care group were listed for kidney transplant (44% vs 16%) and had an optimal KRT start (53% vs 44%). Receipt of interdisciplinary care was associated with a higher odds (OR, 5.73; 95% CI, 2.78-11.80; P < 0.001) of transplant listing compared with usual care after adjusting for important sociodemographic and clinical factors. The odds of an optimal KRT start also favored interdisciplinary care (OR, 1.60; 95% CI, 0.88-2.89; P = 0.12) but did not achieve statistical significance.

Limitations

The study was non-randomized and had a small sample size.

Conclusions

Interdisciplinary care is associated with better ESKD preparedness compared with usual nephrology care alone in racial and ethnic minorities. Larger studies are needed to determine the effectiveness of interdisciplinary care in patients with advanced CKD.

Optimising Access Surgery in Senior Haemodialysis Patients (OASIS): study protocol for a multicentre randomised controlled trial

INTRODUCTION

Current evidence on vascular access strategies for haemodialysis patients is based on observational studies that are at high risk of selection bias. For elderly patients, autologous arteriovenous fistulas that are typically created in usual care may not be the best option because a significant proportion of fistulas either fail to mature or remain unused. In addition, long-term complications associated with arteriovenous grafts and central venous catheters may be less relevant when considering the limited life expectancy of these patients. Therefore, we designed the Optimising Access Surgery in Senior Haemodialysis Patients (OASIS) trial to determine the best strategy for vascular access creation in elderly haemodialysis patients.

METHODS AND ANALYSIS

OASIS is a multicentre randomised controlled trial with an equal participant allocation in three treatment arms. Patients aged 70 years or older who are expected to initiate haemodialysis treatment in the next 6 months or who have started haemodialysis urgently with a catheter will be enrolled. To detect and exclude patients with an unusually long life expectancy, we will use a previously published mortality prediction model after external validation. Participants allocated to the usual care arm will be treated according to current guidelines on vascular access creation and will undergo fistula creation. Participants allocated to one of the two intervention arms will undergo graft placement or catheter insertion. The primary outcome is the number of access-related interventions required for each patient-year of haemodialysis treatment. We will enrol 195 patients to have sufficient statistical power to detect an absolute decrease of 0.80 interventions per year.

ETHICS AND DISSEMINATION

Because of clinical equipoise, we believe it is justified to randomly allocate elderly patients to the different vascular access strategies. The study was approved by an accredited medical ethics review committee. The results will be disseminated through peer-reviewed publications and will be implemented in clinical practice guidelines.

TRIAL REGISTRATION NUMBER

NL7933.

PROTOCOL VERSION AND DATE

V.5, 25 February 2021.

Central Venous Catheters for Hemodialysis-the Myth and the Evidence

Hemodialysis-central venous catheter (HD-CVC) insertion is a most often performed procedure, with approximately 80% of patients with end-stage kidney disease in the United States initiating kidney replacement therapy through a HD-CVC. Certain adverse events arising from HD-CVC placement, including catheter-related bloodstream infections (CR-BSIs), thrombosis, and central vein stenosis, can complicate the clinical course of patients and lead to considerable financial impact on the health care system. Medical professionals with different training backgrounds are responsible for performing this procedure, and therefore, comprehensive operator guidelines are crucial to improve the success rate of HD-CVC insertion and prevent complications. In this review article, we not only discuss the basic principles behind the use of HD-CVCs but also address frequently asked questions and myths regarding catheter asepsis, length selection, tip positioning, and flow rate assessment.

De Novo Central Vein Stenosis in Hemodialysis Patients Following Initial Tunneled Central Vein Catheter Placement

Background

Central vein stenosis (CVS) is a common complication in hemodialysis patients following tunneled central venous catheter (CVC) insertion. Little is known about its incidence, association with patient characteristics, or relationship with duration of CVC placement. We systematically evaluated central vein stenosis in hemodialysis patients receiving their first CVC exchange at a large medical center.

Methods

All new hemodialysis patients underwent an ultrasound before their internal jugular tunneled CVC placement, to exclude venous stenosis or thrombosis. After the initial CVC insertion, if the patients were referred for CVC exchange due to dysfunction, a catheterogram/venogram was performed to assess for hemodynamically significant (≥50%) central vein stenosis. During a 5-year period (January 2016 to January 2021), we quantified the incidence of CVS in patients undergoing CVC exchange. We also evaluated the association of central vein stenosis with patient demographics, comorbidities, and duration of CVC dependence before exchange.

Results

During the study period, 273 patients underwent exchange of a tunneled internal jugular vein CVC preceded by a catheterogram/venogram. Hemodynamically significant CVS was observed in 36 patients (13%). CVS was not associated with patient age, sex, race, diabetes, hypertension, coronary artery disease, peripheral artery disease, or CVC laterality. However, the frequency of CVS was associated with the duration of CVC dependence (26% versus 11% for CVC duration ≥6 versus <6 months: odds ratio (95% CI), 3.17 (1.45 to 6.97), P=0.003).

Conclusions

Among incident hemodialysis patients receiving their first tunneled internal jugular CVC exchange, the overall incidence of de novo hemodynamically significant central vein stenosis was 13%. The likelihood of CVS was substantially greater in patients with at least 6 months of CVC dependence.

The failing kidney allograft: A review and recommendations for the care and management of a complex group of patients

The return to dialysis after allograft failure is associated with increased morbidity and mortality. This transition is made more complex by the rising numbers of patients who seek repeat transplantation and therefore may have indications for remaining on low levels of immunosuppression, despite the potential increased morbidity. Management strategies vary across providers, driven by limited data on how to transition off immunosuppression as the allograft fails and a paucity of randomized controlled trials to support one approach over another. In this review, we summarize the current data available for management and care of the failing allograft. Additionally, we discuss a suggested plan for immunosuppression weaning based upon the availability of re-transplantation and residual allograft function. We propose a shared-care model in which there is improved coordination between transplant providers and general nephrologists so that immunosuppression management and preparation for renal replacement therapy and/or repeat transplantation can be conducted with the goal of improved outcomes and decreased morbidity in this vulnerable patient group.

Association of Insurance Status with Timing of Hemodialysis Access Placement

OBJECTIVE

Patients without adequate outpatient follow-up often present requiring emergency hemodialysis and then undergo permanent dialysis access placement at a later time. We sought to examine the relationship between type of insurance and whether a patient was already on dialysis at time of surgery.

METHODS

The Vascular Quality Initiative Hemodialysis Access registry was queried for all adult patients undergoing first time permanent hemodialysis access between January 2015 and September 2019. Patient and procedural characteristics were examined in patients split by private insurance, Medicare over 65 years, Medicare under 65 years, and Medicaid. Primary Outcome was whether patients were on dialysis at time of surgery.

RESULTS

There were 19,307 adult patients that underwent first time placement of an arterio-venous fistula or graft. Of these patients, 9,729 (50%) had Medicare, 7,179 (37%) had private insurance, and 2,399 (12%) had Medicaid. The patients with Medicare were sub-grouped by age with 2,968 (31%) being under the age of 65 and 6,761 (69%) being over the age of 65. Patients with Medicare and under 65 were the most likely to be on dialysis at the time of surgical access placement at 67%, while 59% of Medicaid patients were on dialysis, and 53% each group of patients with Medicare and over 65 and private insurance were on dialysis. Following adjustment for patient characteristics, patients with Medicare under 65 and over 65 were both significantly more likely to be on dialysis at time of surgery compared to private insurance with odds ratio of 1.64 (95% confidence interval 1.49-1.80, p <0.001) and odds ratio of 1.11 (95% confidence interval 1.03-1.20, p = 0.007), respectively. After adjustment, patients with Medicaid were no longer significantly more likely to be on dialysis. Secondary outcomes demonstrated, after adjustment, no difference in association with surgical fistula versus graft in any insurance groups, however patients with Medicare and under 65 were more likely to have a non-radial artery used for anastomosis with an odds ratio of 1.18 (95% confidence interval 1.04-1.34, p = 0.011).

CONCLUSIONS

Certain types of insurance are correlated with being on dialysis at the time of access placement. Although associations were seen between insurance type and surgical access characteristics, these were predominantly insignificant when patient demographics and status of dialysis were controlled for. These potential gaps in care represent an area for improvement that deserves further exploration.

Quantifying The Costs of Creating and Maintaining Hemodialysis Access in An All-Payer Rate-Controlled Health System

OBJECTIVES

The creation and maintenance of durable hemodialysis access is critically important for reducing patient morbidity and controlling overall costs within health systems. Our objective was to quantify the costs associated with hemodialysis access creation and its maintenance over time within a rate-controlled health system where charges equate to payments.

METHODS

The Maryland Health Services Cost Review Commission administrative claims database was used to identify patients who underwent first-time access creation from 2012-2020. Patients were identified using CPT codes for access creation, and costs were accrued for the initial encounter and all subsequent outpatient access-related encounters. T-tests and Wilcoxon tests were used to compare reinterventions and access-related costs ($USD) between arteriovenous fistulae (AVF) and arteriovenous grafts (AVG). Multivariable modeling was used to quantify the association of access type with charge variation.

RESULTS

Overall, 12,716 patients underwent first-time access creation (69.3% AVF vs. 30.7% AVG). There was no difference in freedom from reintervention between the two access types at any point following creation (HR: 1.03, 95%CI: 0.97-1.10); however, AVF were associated with a lower number of cumulative reinterventions (1.50 vs. 2.24) compared to AVG (P<0.0001). AVF was associated with lower overall costs in the year of creation ($9,388 vs. $13,539, P<0.0001), a difference that remained significant over the subsequent 3 years. The lower costs associated with AVF were present both in the costs associated with creation and subsequent maintenance. On multivariable analysis, AVF was associated with a $3,557 reduction in total access-related costs versus AVG (95%CI -$3828, -3287).

CONCLUSION

AVF require fewer interventions and are associated with lower costs at placement and over the first three years of maintenance compared to AVG. The use of AVF for first-time hemodialysis access represents an opportunity for healthcare savings in appropriately selected patients with a high preoperative likelihood of AVF maturation.

Arteriovenous Vascular Access-Related Procedural Burden Among Incident Hemodialysis Patients in the United States

RATIONALE & OBJECTIVE

As the proportion of arteriovenous fistulas (AVFs) compared with arteriovenous grafts (AVGs) in the United States has increased, there has been a concurrent increase in interventions. We explored AVF and AVG maturation and maintenance procedural burden in the first year of hemodialysis.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

Patients initiating hemodialysis from July 1, 2012, to December 31, 2014, and having a first-time AVF or AVG placement between dialysis initiation and 1 year (N = 73,027), identified using the US Renal Data System (USRDS).

PREDICTORS

Patient characteristics.

OUTCOME

Successful AVF/AVG use and intervention procedure burden.

ANALYTICAL APPROACH

For each group, we analyzed interventional procedure rates during maturation maintenance phases using Poisson regression. We used proportional rate modeling for covariate-adjusted analysis of interventional procedure rates during the maintenance phase.

RESULTS

During the maturation phase, 13,989 of 57,275 patients (24.4%) in the AVF group required intervention, with therapeutic interventional requirements of 0.36 per person. In the AVG group 2,904 of 15,572 patients (18.4%) required intervention during maturation, with therapeutic interventional requirements of 0.28 per person. During the maintenance phase, in the AVF group 12,732 of 32,115 patients (39.6%) required intervention, with a therapeutic intervention rate of 0.93 per person-year. During maintenance phase, in the AVG group 5,928 of 10,271 patients (57.7%) required intervention, with a therapeutic intervention rate of 1.87 per person-year. For both phases, the intervention rates for AVF tended to be higher on the East Coast while those for AVG were more uniform geographically.

LIMITATIONS

This study relies on administrative data, with monthly recording of access use.

CONCLUSIONS

During maturation, interventions for both AVFs and AVGs were relatively common. Once successfully matured, AVFs had lower maintenance interventional requirements. During the maturation and maintenance phases, there were geographic variations in AVF intervention rates that warrant additional study.

Patency and functionality of radiocephalic arteriovenous fistulas with an external support device (VasQ™): Real-world single-center experience

BACKGROUND

The VasQTM device was designed to improve the outcome of arteriovenous fistulae by optimizing the hemodynamics of the flow in the juxta-anastomotic region of the arteriovenous fistulae through tailored external support. The aim of the study was to evaluate the impact of the VasQ on outcome of radiocephalic arteriovenous fistulae in a real-world setting.

METHODS

This was a single-center, retrospective analysis of patients with either fistula creation before or after dialysis initiation with implantation of the VasQ device during creation of end-to-side radiocephalic arteriovenous fistulae between June 2018 and May 2019. The flow rate and vein diameter were evaluated intraoperatively, at discharge within 48 h postprocedure and at a follow-up of 1, 3, 6, 9, and 12 months.

RESULTS

Thirty-three VasQ devices were implanted during 33 radiocephalic arteriovenous fistula procedures. The study population comprised mostly of men, with an average age of 66 years. Mean intraoperative flow was 428 mL/min (range: 130-945). All patients were discharged with patent arteriovenous fistulae and mean fistula flow of 740 mL/min (range: 230-1300 mL/min). The primary patency was 100% and 79% at 3 and 6 months, respectively. Cumulative/secondary patency was 100% and 90% at 3 and 6 months, respectively.

CONCLUSION

Data presented here suggest that the VasQ device has the potential to provide benefit to the functionality of radiocephalic arteriovenous fistulae.

Economic Impact of Home Hemodialysis

Home hemodialysis (HD) is growing in the United States, but the economics of the modality are largely unknown, especially considering the unique aspects of home HD in the United States . In this review, I focus on details of Medicare coverage, which directly applies to most patients on dialysis and influences the policies of private insurers. Key details in Medicare comprise the relationship between home dialysis training and initial Medicare eligibility, reimbursement for home HD training, coverage of additional HD treatments (ie., in excess of 3 treatments per week), and monthly capitated payments to nephrologists. The overarching narrative is that frequent home HD directly increases Medicare costs for outpatient dialysis, but these added costs can be mitigated by lower inpatient expenditures if increased HD treatment frequency lowers the risk of cardiovascular hospitalization and infection control is emphasized. I also review recent international literature; conventional home HD exhibits a superior cost profile, whereas frequent home HD is generally cost-effective over multiple treatment years (ie, if early technique failure is avoided). Out-of-pocket expenses for patients should be considered. The future economics of home HD in the United States will be determined by new equipment, new adaptations of the modality, and new payment models.

Dialysis Vascular Access: Where do Tunneled Catheters Stand? - A Single-Center Experience

Introduction

Tunneled cuffed catheters (TCC) provides a short and intermediate-term access solution for dialysis patients who fail to get an arteriovenous fistula (AVF). They are associated with high morbidity and mortality along with high rates of infectious complications.

Methods

We present a single-center prospective cohort of 159 TCCs inserted over one year. Patients were dialyzed in-hospital and in various peripheral dialysis units attached to the institute. The primary endpoint was catheter drop-out.

Results

The mean age of patients was 41.8 ± 16.9 years. The right internal jugular vein was the commonest site of TCC insertion (66%). The absence of suitable veins was the predominant reason for TCC insertion. The mean time to catheter drop-out was 134.4 ± 83.3 days (5-399 days). Death with a working catheter was the most common cause of catheter drop-out (22.6%). About 25% of catheters were lost to catheter-related bloodstream infections (CRBSI), either alone or as overlap with poor flow. CRBSI rates were 3.74 episodes per 1000 catheter-days. No difference in survival between the staggered tip and split-tip catheters was found.

Conclusions

With the advent of the "hub and spoke" model for dialysis in the public sector healthcare, TCCs are suboptimal with regards to patient and catheter survival, with high infection rates. It must be regarded as a temporary solution and AVF creation should be prioritized.

Utility of Blood Flow/Resistance Index Ratio (Qx) as a Marker of Stenosis and Future Thrombotic Events in Native Arteriovenous Fistulas

Objective: The resistance index (RI) and the blood flow volume (Q_a) are the most used Doppler ultrasound (DUS) parameters to identify the presence of stenosis in arteriovenous fistula (AVF). However, the reliability of these indexes is now matter of concern, particularly in predicting subsequent thrombosis. In this study, we aimed at testing the diagnostic capacity of the Q_a/RI ratio (Q_x) for the early identification of AVF stenosis and for thrombosis risk stratification.

Methods: From a multicentre source population of 336 HD patients, we identified 119 patients presenting at least one “alarm sign” for clinical suspicious of stenosis. Patients were therefore categorized by DUS as stenotic (n = 60) or not-stenotic (n = 59) and prospectively followed. Q_a, RI, and Q_X, together with various clinical and laboratory parameters, were recorded.

Results: Q_a and Q_x were significantly higher while RI was significantly lower in non-stenotic vs. stenotic patients (p < 0.001 for each comparison). At ROC analyses, Q_x had the best discriminatory power in identifying the presence of stenosis as compared to Q_a and RI (AUCs 0.976 vs. 0.953 and 0.804; p = 0.037 and p < 0.0001, respectively). During follow-up, we registered 30 thrombotic events with an incidence rate of 12.65 (95% CI 8.54–18.06) per 100 patients/year. In Cox-regression proportional hazard models, Q_x showed a better capacity to predict thrombosis occurrence as compared to Q_a (difference between c-indexes: 0.012; 95% CI 0.004–0.01).

Conclusions: In chronic haemodialysis patients, Q_x might represent a more reliable and valid indicator for the early identification of stenotic AVFs and for predicting the risk of following thrombosis.

Effect of preoperative exercise on vascular caliber and maturation of arteriovenous fistula: the physicalfav trial, a randomized controlled study

BACKGROUND AND OBJECTIVES

Autologous arteriovenous fistula (AVF) is the best vascular access for hemodialysis. Distal forearm radiocephalic fistula is the best option, although the primary failure rate ranges from 20% to 50%. The main objective of the PHYSICALFAV trial was to evaluate the effect of preoperative isometric exercise on vascular caliber, percentage of distal arteriovenous fistula, and primary failure rate.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

The PHYSICALFAV trial (NCT03213756) is an open-label, multicenter, prospective, randomized, controlled trial (RCT). A total of 138 patients were randomized 1:1 to the exercise group (exercises combining a handgrip device and an elastic band for 8 weeks) or the control group (no exercise) and followed up with periodic Doppler ultrasound (DU) examinations.

RESULTS

After 8 weeks of preoperative isometric exercise, in the exercise group, significant increases were detected in venous caliber (2.80 ± 0.95 mm vs 3.52 ± 0.93 mm [p < 0.001]), arterial caliber (2.61 ± 0.82 mm vs 2.74 ± 0.80 mm [p = 0.008]), arterial peak systolic velocity (66.34 ± 19.2 cm/s vs 71.03 ± 21.5 cm/s [p 0.043]), and maximum strength (28.35 ± 9.16 kg vs 32.68 ± 10.8 kg [p < 0.001]). Distal radiocephalic fistulas were performed in 75% of the exercise group patients compared with 50.8% in the control group (p = 0.030). The global primary failure rate was very low in both groups (7% exercise group vs 14% control group [p = 0.373]).

CONCLUSION

Isometric preoperative exercise can improve vascular caliber and increase the possibility of performing distal arteriovenous fistula, with no significant differences in primary failure rate.