Medicare Costs Associated With Arteriovenous Fistulas Among US Hemodialysis Patients

Enhancing Calcium Phosphate Cements: A review of Bacterial Cellulose (BC) and other Biopolymer Reinforcements for Biomedical Applications

Calcium phosphate cements (CPCs) are renowned for their biocompatibility and osteoconductivity, making them ideal for bone tissue engineering. However, their brittleness and low tensile strength limit their use in load-bearing applications. Bacterial cellulose (BC) has emerged as a promising reinforcement material due to its high tensile strength, biocompatibility, and biodegradability. The incorporation of 2 wt% BC into CPCs increased compressive strength from 5 MPa to 12 MPa, representing a 2.4-fold enhancement, while also improving toughness and promoting cellular interactions through its nanofibrillar structure. Additionally, hybrid composites combining BC with collagen, chitosan, or polycaprolactone (PCL) exhibit synergistic effects, further enhancing mechanical properties and biodegradability. These advancements highlight the potential of BC-reinforced CPCs for clinical applications in bone repair and regeneration. Despite these improvements, limited research addresses tensile and flexural properties, which are critical for load-bearing applications, as well as the effects of BC on injectability and setting time for minimally invasive procedures. Emerging innovations, such as electroactive BC-reinforced CPCs for stimulating bone healing, hold significant potential but remain underexplored. Future research should focus on optimising mechanical properties, validating clinical performance, and developing hybrid formulations to expand their use in load-bearing bone repairs.

Interplay between Skeletal Muscle Catabolism and Remodeling of Arteriovenous Fistula by Yes-Associated Protein 1 (YAP1) Signaling

Key Points

Background

Arteriovenous (AV) fistulas are the preferred access for dialysis but have a high incidence of failure. The aim of this study was to understand the crosstalk between skeletal muscle catabolism and AV fistula maturation failure.

Methods

Skeletal muscle metabolism and AV fistula maturation were evaluated in mice with CKD. The roles of myostatin and yes-associated protein 1 (YAP1) in regulating the transdifferentiation of adventitial mesenchymal stem cells (MSCs) and intima hyperplasia in AV fistula were investigated. Nanoparticles carrying a YAP1 inhibitor, verteporfin, with light irradiation–controlled release were synthesized and applied to AV fistula.

Results

Increased trichrome signals and stenosis were observed in AV fistulas from mice treated with myostatin and from mice with CKD. By contrast, blocking myostatin function with an anti-myostatin peptibody not only improved body weight and muscle size in CKD mice but also decreased neointima formation in AV fistulas. In cultured MSCs, myostatin induced YAP1 expression, promoting the differentiation of MSCs into myofibroblasts and inducing extracellular matrix deposition. Red light irradiation–controlled release of verteporfin from nanoparticles blocked YAP1 activation and alleviated myostatin-induced MSC activation. Periadventitial application and red light irradiation of nanoparticles carrying verteporfin significantly suppressed stiffening and neointima formation in AV fistula.

Conclusions

CKD induced muscle wasting, leading to increased production of myostatin, which stimulated MSC activation and vascular fibrosis linked to AV fistula stenosis. YAP1 signaling was activated in these processes. Red light irradiation–controlled release of verteporfin offered a feasible approach for local vascular drug intervention to improve AV fistula maturation.

The Long-Term Patency Rate and Factors Influencing Dysfunction of the Autogenous Arteriovenous Fistula in Hemodialysis Patients: A Retrospective Study

INTRODUCTION

Autogenous arteriovenous fistula (AV fistula) dysfunction continues to be a widespread clinical challenge, adversely impacting both patients and society as a whole. The aim of this study was to investigate the long-term patency rate of AV fistula, explore the factors that contribute to AV fistula dysfunction, and present the findings in a way that can guide clinical practice.

METHODS

This retrospective cohort study enrolled patients who underwent AV fistula creation and subsequent hemodialysis at a tertiary A-level hospital in Chongqing, China. Demographic, clinical, and laboratory characteristics of the patients, as well as AV fistula dysfunction, were retrospectively reviewed from electronic health records. Cox proportional hazards regression analysis was used to analyze the factors influencing AV fistula dysfunction, and a forest plot was created to visualize the results. Additionally, Kaplan-Meier survival analysis was used to analyze AV fistula survival.

FINDINGS

This study analyzed 226 patients undergoing hemodialysis, demonstrating cumulative AV fistula patency rates of 82.1% at 12 months, 60.7% at 36 months, 45.4% at 60 months, and 33.5% at 84 months. Univariate Cox proportional hazard regression analysis identified six variables associated with AV fistula dysfunction (p < 0.1): body mass index (BMI), preemptive AV fistula creation, diabetes, total cholesterol, albumin, and uric acid. Subsequent multivariate analysis revealed four independent predictors for dysfunction: elevated BMI (HR: 1.58, p = 0.016), preemptive AV fistula creation (HR: 0.67, p = 0.029), albumin (HR: 2.83, p < 0.001), and uric acid (HR: 1.57, p = 0.020).

DISCUSSION

Our study findings indicated that overweight, hypoalbuminemia, and high concentrations of uric acid were independent risk factors for AV fistula dysfunction. In contrast, preemptive AV fistula creation was an independent protective factor against AV fistula dysfunction. Therefore, early interventions and surveillance for these factors should be performed to improve long-term AV fistula patency rates.

Six-month safety and efficacy outcomes from the randomized-controlled arm of the WRAPSODY Arteriovenous Access Efficacy (WAVE) trial

Stenosis within the arteriovenous fistula (AVF) of hemodialysis patients leads to vascular access dysfunction and inadequate hemodialysis. Percutaneous transluminal angioplasty (PTA) is the standard therapy for stenosis. However, rates of restenosis and loss of access patency remain high. Outcomes of a novel cell-impermeable endoprosthesis (CIE) have not been investigated in this setting. Therefore, our study was designed to address this as a prospective, international, multicenter pivotal trial (NCT04540302) with 245 patients with stenosis in their venous outflow circuit randomized to treatment: 122 receiving CIE and 123 receiving PTA across 43 international centers. Primary endpoints included target lesion primary patency (TLPP) at six months (freedom from clinically driven target lesion revascularization or target lesion thrombosis) and freedom from safety events through 30 days post-index procedure that affected the access circuit and resulted in reintervention, hospitalization, or death. Access circuit primary patency (ACPP) was evaluated as a secondary efficacy endpoint. Six-month TLPP and ACPP were significantly higher for the CIE cohort versus PTA (TLPP: 89.6% vs. 62.3%; ACPP: 72.2% vs. 57.0%). Thirty days post-index procedure, there was no statistically significant difference in the freedom from safety events for the CIE versus PTA (96.6 vs. 95.0%). No differences were observed in adverse events between either cohort. Our study shows that among patients with stenosis in their AVF, the CIE was superior to PTA with respect to six-month TLPP and ACPP with no observed difference in 30-day primary safety events.

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.

Insights into the real-world practice of vascular access care pathways in Italy: data from a national survey

BACKGROUND

International guidelines issued recommendations for vascular access (VA) care for hemodialysis, but there are no registry data regarding this topic in Italy.

METHODS

A survey consisting of 17 items was sent to all Italian dialysis wards, via the Italian Society of Nephrology (SIN) website, from April to June 2021. The items were defined, discussed and approved by experts in vascular access management within the Italian Society of Nephrology. A total of 124 dialysis units answered, accounting for 14% of all dialysis units. The survey thus encompasses all regions within the country, with some regional variations in terms of adherence.

RESULTS

One hundred twenty-four facilities provided data, regarding 12,276 patients: 61% had an arteriovenous fistula (AVF), 34% had a central venous catheter (CVC), and 5% had an arteriovenous graft (AVG). Among them, two-thirds of the facilities reported having a vascular access care pathway, formally standardized in 79% of cases. Forty-six % of centers had a fully equipped vascular access care pathway, encompassing preoperative mapping (80%), vascular access setup (71%), arteriovenous fistula maturation monitoring (76%), first-level (80%) and second-level (78%) monitoring, and surgical and/or endovascular treatment of complications (66%). Vascular access monitoring was computerized in 39% of facilities. First-level monitoring (physical examination) was primarily done by nurses in two-thirds of facilities. Of note, 45% of centers had nurses who were skilled in ultrasound-guided cannulation. Quite surprisingly, facilities with less than 100 patients had a greater prevalence of arteriovenous fistulas than those with more than 100 patients (p = 0.0023). A protocolled vascular access care pathway was associated with a higher likelihood of having an arteriovenous fistula (70% AVF vs 42,1% CVC; p = 0.04). The presence in the facility of interventional nephrologists or nurses with ultrasound-guided cannulation skills significantly reduced the prevalence of central venous catheters.

CONCLUSION

These survey data further strengthen the need for formal and shared vascular access monitoring protocols.

Prospective Analysis of Arteriovenous Fistula Performance in the Context of Competing Risks

Key Points

Among 257 newly created arteriovenous fistulas, primary nonfunction occurred in 49%, and only 55% were ultimately used for dialysis. Loss of arteriovenous fistula patency was lower when competing risks were accounted for compared with conventional Kaplan–Meier analysis. We present icon-array plots that summarize our data and may be used a decision aid for patients in the future.

Background

Many patients with newly created arteriovenous fistulas (AVFs) may die before the AVF is needed for hemodialysis. However, formal competing risks (CRs) frameworks are rarely used to report AVF patency, which may lead to biased estimates. We sought to identify the proportion of newly created AVF experiencing primary nonfunction and describe long-term patency using a CR framework.

Methods

We conducted a prospective observational study in 257 adults with newly created AVF in Alberta, Canada. The primary outcome was primary nonfunction. Secondary outcomes included loss of primary patency, loss of assisted primary patency, and loss of secondary functional patency. Results were presented using icon-array plots to form the basis for future decision aids.

Results

Participants were 63.0% male, with mean age 62.3 years and median follow-up 18.5 months (range, 0.02–180 months). Of 257 participants, 50 could not be assessed for function or primary nonfunction, usually because of death. Of the remaining 207, 102 (49.3%) had primary nonfunction, and function was ultimately established for 142 (68.6%). Thus, only 142 of the 257 participants (55.3%) ultimately used the AVF for hemodialysis. High rates of CRs led to biased results from Kaplan–Meier analyses of lost patency. When accounting for CRs, loss of primary patency among AVFs with established function was 36.6%, 65.5%, and 66.2%, at 1, 3, and 5 years, respectively.

Conclusions

Only 55% of fistulas were ultimately used for hemodialysis when accounting for CRs and primary nonfunction. These results and the icon-array plots may inform discussions surrounding vascular access options for patients.

A randomized controlled trial evaluated the efficacy and safety of apixaban for prevention of recurrent thrombosis after thrombectomy of hemodialysis vascular access

Dialysis vascular access thrombosis poses a substantial challenge for individuals undergoing hemodialysis. The efficacy and safety of apixaban, a direct oral coagulation factor Xa inhibitor, in preventing recurrent access thrombosis have yet to be explored. Here, a multicenter randomized control study (NCT04489849) enrolled hemodialysis patients to evaluate this who underwent successful endovascular thrombectomy within 48 hours. Participants were assigned to standard care or standard care plus apixaban, 2.5 mg twice daily for three months. The trial design involved open-label administration, with independent adjudication of endpoints. The primary efficacy endpoint was recurrent access thrombosis within three months after thrombectomy. A total of 186 patients with well-balanced baseline characteristics were enrolled, 93 randomized to the apixaban group and 93 to the control group. The apixaban group demonstrated a significantly lower rate of access thrombosis at three months than the control group (24.0% vs. 40.8%; hazard ratio, 0.52 [95% confidence interval 0.31-0.88]), along with a significantly better primary patency failure rate (32.2% vs. 49.5%, 0.57 [0.36-0.91]). Safety outcomes showed comparable death rates and major bleeding incidents but significantly higher incidence of minor bleeding in the apixaban group (22.6% vs. 7.5%). The effect of apixaban did not show interaction in subgroups of different access types, antiplatelet usage, severity of comorbidities, or history of thrombosis. Thus, apixaban effectively reduced the risk of recurrent thrombosis in hemodialysis vascular access post-thrombectomy. Despite a minor increase in bleeding adverse effects, the net clinical benefit favors the use of apixaban in this context.

Assessment of photobiomodulation in response to the microcirculation in arteriovenous fistula for hemodialysis patient

Background

Management of blood flow in arteriovenous fistula (AVF) is a critical clinical issue for hemodialysis (HD) patients.

Objectives

To determine the effect of microcirculation of AVF in HD patients with photobiomodulation (PBM).

Methods

Twenty HD patients were enrolled in this study. PBM was used to radiate the palm of HD patients at a total dose of 126 J, and the microcirculatory analysis in AVF was investigated.

Results

Among the patients <65 years old, there is an increase of 2.31% and 1.37% in the average velocity and flux in AVF, respectively. This increase is higher than those observed in patients aged >65 years old. Additionally, the cumulative effect of the 830 nm laser was observed for at least 10 min, resulting in continuous increases of 3.16% in velocity and 1.59% in flux for HD patients <65 years old. On the contrary, the average velocity and flux in AVF increased in patients who had undergone HD for <6 years.

Conclusions

In this study, the age and the duration of HD treatment are the two factors that influence microcirculation in HD patients with PBM. The results suggest that PBM could be used to improve the average velocity and flux in AVF, particularly for younger patients with shorter HD treatment durations.

Bismuth-infused perivascular wrap facilitates delivery of mesenchymal stem cells and attenuation of neointimal hyperplasia in rat arteriovenous fistulas

BACKGROUND

Mesenchymal stem cells (MSCs) have emerged as novel therapies for supporting arteriovenous fistula (AVF) maturation, and bioresorbable polymeric scaffolds have enabled sustained MSC delivery into maturing AVFs. However, the radiolucency of biopolymeric wraps prevents in vivo monitoring of their integrity and location, hindering long-term preclinical investigations.

METHODS

We infused bismuth nanoparticles (BiNPs) into polycaprolactone (PCL) to fabricate an electrospun perivascular wrap capable of MSC delivery and conducive to longitudinal monitoring using conventional imaging. We tested the wraps' effects on the attenuation of markers of neointimal hyperplasia (i.e., endothelial dysfunction, hypoxia, and inflammation), the leading cause of AVF failure, in rats with induced chronic kidney disease (n = 3 per time point) for the following groups: control (no wrap), PCL wrap, PCL with MSCs, PCL-Bi (BiNP-infused wrap), and PCL-Bi with MSCs.

RESULTS

Physicochemical characterization and in vitro biocompatibility tests revealed that BiNP infusion did not alter the wrap's non-cytotoxicity toward vascular cells, hemocompatibility, and capacity for MSC loading but facilitated long-term monitoring via micro-computed tomography. After 8 weeks, all treatment groups demonstrated significant improvement in wall-to-lumen ratio on ultrasonography (P < 0.001), neointima-to-lumen ratio on histomorphometry (P < 0.001), and attenuation of neointimal hypoxia on immunohistochemistry (P < 0.05). Compared to non-MSC wraps, MSC-loaded wraps not only attenuated endothelial dysfunction and neointimal inflammation but also reduced hypoxia and inflammation across all vascular layers.

CONCLUSION

These results demonstrate that MSC delivery through a radiopaque polymeric wrap could enhance AVF patency outcomes through the inhibition of multiple pathways inducing AVF failure.

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.

Outcomes Following Arteriovenous Fistula Creation in Medicare Beneficiaries With End-Stage Kidney Disease

The objective of this study was to measure the contemporary patency rates and frequency of interventions required for arteriovenous fistula (AVF) care in a representative US population of patients with end-stage kidney disease, including by age, race, and gender. All Medicare beneficiaries aged >20 years who underwent AVF graft creation for end-stage kidney disease between 2017 and 2019 were included for analysis. The primary end points included primary patency, primary assisted patency, postintervention patency, and fistula functionality up to 1 year after AVF placement. The secondary end point included admission for an associated adverse event after AVF creation. Multivariate analysis of patency rates was also assessed. Of 43,457 patients included in the analysis, the cumulative primary patency at 90 days was 68.4% and at 1 year, 31.5%. At 1 year, the primary assisted patency rate, postintervention patency, and fistula use were 70.4%, 30.2%, and 59.1%, respectively. There was no difference in primary patency rates when comparing age groups (age 40 to 59 years: hazard ratio [HR] 1.01, 95% confidence interval [CI] 0.95 to 1.06, p = 0.84 or age ≥60 years: HR 0.99, 95% CI 0.93 to 1.04, p = 0.61) with the reference of age group 20 to 39 years. Women were at greater risk of experiencing primary patency failure than were men (HR 1.16, 95% CI 1.14 to 1.20, p <0.001), and Black patients were at greater risk of experiencing primary patency failure than were White patients (HR 1.34, 95% CI 1.31 to 1.38, p <0.001). The cumulative incidence of admissions for adverse events was 32.6% at 1 year. In conclusion, our findings suggest that the real-world AVF patency rates remain low, with disproportionately low rates in women and Black patients.

Long-Term Outcomes of Subcutaneous Versus Transvenous Implantable Cardioverter Defibrillator Use Among Patients on Maintenance Dialysis

BACKGROUND

Despite an elevated risk of sudden cardiac death among dialysis patients, implantable cardioverter defibrillators (ICDs) have not been shown to improve mortality and are associated with high complication rates. Subcutaneous (S-)ICDs may reduce the risk of complications for eligible dialysis patients, but safety and benefits vs transvenous (TV-ICDs are unknown.

OBJECTIVE

To compare long-term outcomes between dialysis patients receiving S-ICD vs TV-ICDs.

METHODS

We performed a retrospective analysis of ICD implants among Fee-For-Service Medicare beneficiary dialysis patients in the National Cardiovascular Data Registry ICD Registry. Outcomes were ascertained from Medicare claims data. We compared survival outcomes, hospital admissions, and ICD-associated and dialysis vascular access-associated complications, between eligible S-ICD and single-chamber TV-ICD recipients using stabilized inverse probability of treatment weighting.

RESULTS

We identified 529 dialysis patients receiving S-ICDs and 842 receiving single-chamber TV-ICDs who met the inclusion criteria. S-ICD recipients were younger, more often Black, and had a higher burden of cardiac disease and prior dialysis access interventions. After propensity weighting, there was no difference in the risk of death (hazard ratio [HR], 1.12, 95% confidence interval [CI], 0.96-1.30), hospital admission (HR, 1.01; 95% CI, 0.88-1.16), bacteremia or sepsis (HR, 1.01; 95% CI, 0.80-1.26), device reoperation (HR, 1.06; 95% CI, 0.59-1.89), and subsequent dialysis access interventions (HR, 1.12; 95% CI, 0.86-1.46).

CONCLUSION

In this representative longitudinal cohort study of dialysis patients, compared with TV-ICD, S-ICD was not associated with decreased risks of death, hospitalization, device complications, or dialysis access interventions.

Advancements in Mesenchymal Stem Cell-Based Therapy for Enhancing Arteriovenous Fistula Patency

Chronic kidney disease (CKD) affects more than 10% of the world's population. Hemodialysis, along with peritoneal dialysis and renal transplant, is one of the renal replacement therapies offered to patients with CKD/end-stage renal disease (ESRD). To proceed with hemodialysis, vascular access is required. The two means of long-term access are arteriovenous fistula (AVF) and arteriovenous graft (AVG). Multiple therapies have been created to help the long-term patency of AVFs. These therapies are needed as 40% of AVFs fail within the first year and additional intervention is required. Much of the existing research has focused on biomarkers, immune cells, hypoxia, and cell-based therapies. Regeneration therapy using mesenchymal stem cells seeks to investigate other ways that we can treat AVF failure. Mesenchymal stem cells are harvested as two main types, fetal and adult. Fetal cells are harvested at different times in fetal gestation and from multiple sources, placental blood, Whartons jelly, and amniotic stem cell fluid. Taken together, this review summarizes the different preclinical/clinical studies conducted using different types of MSCs towards vascular regenerative medicine and further highlights its potential to be a suitable alternative approach to enhance AVF patency.

The price of dialysis access: Implications of access type and patient-centric approaches to cost

PURPOSE

This study explores out-of-pocket (OOP) costs for patients and provider reimbursement for dialysis access creation. It aims to illustrate the financial characteristics of four dialysis access modalities to consider in decision-making for clinicians, patients, and payers.

MATERIALS AND METHODS

Retrospective data from the Merative™ MarketScan Commercial Claims and Encounters Databases from 2017 to 2022 was analyzed for patients who received an arteriovenous fistula (AVF), arteriovenous graft (AVG), peritoneal dialysis catheter (PDC), or percutaneous AVF (pAVF). ANOVA and Tukey HSD were used to assess cost differences among the four access modalities overall and in the context of insurance type and service site.

RESULTS

Database extraction resulted in 20,863 unique procedures, comprising of 15,043 AVF, 4759 AVG, 896 PDC, and 165 pAVF. Mean age was 59.2 years (±14.19) and 60.53% of the cohort was male. EPO/PPO plans were the most represented (53.06%) and most procedures were performed in the hospital outpatient department (91.99%). There were significant differences found among OOP cost and reimbursement with respect to procedure type, insurance type, and service site. Overall, pAVF had both the highest cost and reimbursement.

CONCLUSION

Patient OOP costs and provider reimbursement differ significantly based on procedure, insurance type, and service site. While pAVF creation is recognized with high reimbursements due to its complexity and the advanced technology required, it also has the highest OOP costs for patients. To help facilitate adoption of new technologies like pAVF, advocacy efforts should focus on encouraging payers to lower the OOP financial barriers for patients to receive these newer but costlier procedures.

Effectiveness and sustainability of a multidisciplinary care model for patients with hemodialysis access dysfunction

BACKGROUND

A multidisciplinary care model involving the interventional radiologist, vascular surgeon, interventional nephrologist, renal advanced nurse practitioner, and renal coordinators was implemented to improve the care for the patient admitted with dysfunctional hemodialysis access. This study aims to evaluate the effectiveness and sustainability of this multidisciplinary care model.

METHOD

A dedicated interventional nephrology suite was established to perform endovascular procedures for patients admitted with hemodialysis access dysfunction via the emergency department of the hospital. We retrospectively collected data from electronic medical records 1-year before and after the implementation (April 2015). Outcome measures include waiting time for intervention, length of stays (LOS), number of dialysis catheter insertions before the intervention, number of inpatient dialysis required, and success rates of the interventions. The waiting time for intervention and LOS was tracked over the next 3 years to determine the sustainability of the care model.

RESULTS

Eight hundred eighty-one endovascular interventions (314 angioplasties, 567 thrombolysis) were performed on 554 patients. Post-implementation, a greater proportion of intervention was performed within 24 h (238 (50.2%) vs 70 (17.2%), p < 0.001) with lesser proportion of patients requiring bridging hemodialysis via temporary catheter, 156 (32.9%) versus 215 (52.8%), p < 0.001. A shorter median LOS and days-to-intervention were reported, 3 (IQR 2-6) versus 5 days (IQR 3-8), p < 0.001 and 1 (IQR 1-2) versus 3 days (IQR 2-4), p < 0.001 respectively. Less hemodialysis session/patient required, 2 (IQR 1-3) versus 3 (IQR 2-4), p < 0.001. The procedural success rate was greater, 440 (92.8%) versus 355 (87.2%), p = 0.020. Three years following implementation, the proportion of patients who received intervention within 24 h and were discharged within 48 h was reported to be persistently greater, 43% versus 13%, p < 0.001, and 27% versus 6%, p < 0.001 respectively.

DISCUSSION

This multi-disciplinary collaboration demonstrated a sustainable care model in improving the delivery of healthcare services for patients with dysfunctional hemodialysis access.

Efficacy and safety of low dose, weight-based subcutaneous enoxaparin protocol in recurrent arteriovenous access thrombosis

BACKGROUND

This study aims to evaluate the safety and efficacy of a short-term, low dose, weight-based subcutaneous enoxaparin protocol (SEP) in maintaining the patency of arteriovenous (AV) access with recurrent thrombosis.

METHODS

Prospective follow-up of 25 patients who presented to a tertiary institution with recurrent AV access thrombosis and treated with anticoagulation according to SEP following successful thrombectomy. Patency and safety outcomes of SEP were studied.

RESULTS

The participants were 66.4 ± 10.2 years old and predominantly male (60%) and of Chinese ethnicity (72%). The AV accesses had a median age of 1.4 (0.6, 5.6) years with 60% being non-autogenous arteriovenous access while 40% were autogenous arteriovenous access. Thrombolytic agents (urokinase (72%) or alteplase (28%)) were used in all procedures while adjunct thrombectomy device was used in only four procedures. The mean dose of enoxaparin was 36.0 ± 8.2 mg or 0.64 ± 0.1 mg/kg/day for a mean duration 30.0 days (Interquartile range: 27.5, 31.0). One patient developed minor bleeding episode. Kaplan-Meier analysis demonstrated that the mean thrombosis-free survival pre- versus post-SEP adoption was 27.3 (95% CI 17.9-36.7) versus 183.5 (95% CI 100.1-266.9) days (p < 0.001). After adjusting for the type of thrombolytic agent, use of adjunct thrombectomy device, cutting balloon, drug-coated balloon, and stent graft, SEP remained a significant factor associated with longer thrombosis-free patency (HR 0.166: 95% CI 0.070-0.392, p < 0.001).

DISCUSSION

SEP appears to be a feasible and safe thromboprophylaxis method to improve thrombosis-free patency for AV access with recurrent thrombosis.

Hemodialysis Vascular Access: A Historical Perspective on Access Promotion, Barriers, and Lessons for the Future

This review describes the history of vascular access for hemodialysis (HD) over the past 8 decades. Reliable, repeatable vascular access for outpatient HD began in the 1960s with the Quinton-Scribner shunt. This was followed by the autologous Brecia-Cimino radial-cephalic arteriovenous fistula (AVF), which dominated HD vascular access for the next 20 years. Delayed referral and the requirement of 1.5-3 months for AVF maturation led to the development of and increasing dependence on synthetic arteriovenous grafts (AVGs) and tunneled central venous catheters, both of which have higher thrombosis and infection risks than AVFs. The use of AVGs and tunneled central venous catheters increased progressively to the point that, in 1997, the first evidence-based clinical practice guidelines for HD vascular access recommended that they only be used if a functioning AVF could not be established. Efforts to promote AVF use in the United States during the past 2 decades doubled their prevalence; however, recent practice guidelines acknowledge that not all patients receiving HD are ideally suited for an AVF. Nonetheless, improved referral for AVF placement before dialysis initiation and improved conversion of failing AVGs to AVFs may increase AVF use among patients in whom they are appropriate.

The application of blood flow sound contrastive learning to predict arteriovenous graft stenosis of patients with hemodialysis

End-stage kidney disease (ESKD) presents a significant public health challenge, with hemodialysis (HD) remaining one of the most prevalent kidney replacement therapies. Ensuring the longevity and functionality of arteriovenous accesses is challenging for HD patients. Blood flow sound, which contains valuable information, has often been neglected in the past. However, machine learning offers a new approach, leveraging data non-invasively and learning autonomously to match the experience of healthcare professionas. This study aimed to devise a model for detecting arteriovenous grafts (AVGs) stenosis. A smartphone stethoscope was used to record the sound of AVG blood flow at the arterial and venous sides, with each recording lasting one minute. The sound recordings were transformed into mel spectrograms, and a 14-layer convolutional neural network (CNN) was employed to detect stenosis. The CNN comprised six convolution blocks with 3x3 kernel mapping, batch normalization, and rectified linear unit activation function. We applied contrastive learning to train the pre-training audio neural networks model with unlabeled data through self-supervised learning, followed by fine-tuning. In total, 27,406 dialysis session blood flow sounds were documented, including 180 stenosis blood flow sounds. Our proposed framework demonstrated a significant improvement (p<0.05) over training from scratch and a popular pre-trained audio neural networks (PANNs) model, achieving an accuracy of 0.9279, precision of 0.8462, and recall of 0.8077, compared to previous values of 0.8649, 0.7391, and 0.6538. This study illustrates how contrastive learning with unlabeled blood flow sound data can enhance convolutional neural networks for detecting AVG stenosis in HD patients.

Assessment of Sonographic Parameters for Predicting Primary Patency Rate in Hemodialysis Patients With Venous Valve-Related Stenosis

OBJECTIVES

Ultrasonography is more frequently used in patients with arteriovenous fistula (AVF) stenosis. The aim of this study is to use sonographic parameters for predicting primary patency in hemodialysis patients with venous valve-related stenosis (VVRS) who are treated by ultrasound-guided percutaneous transluminal angioplasty (PTA).

METHODS

A total of 229 VVRS patients who underwent PTA between January 2017 and December 2021 were enrolled. Clinical characteristics were retrospectively collected. Sonographic parameters were measured both before and after PTA. Univariate and multivariate Cox analyses were performed to identify independent factors associated with primary patency rate.

RESULTS

All measured sonographic parameters improved after PTA compared to before PTA. Before PTA, the diameter of VVRS > 1.0 mm, age ≤ 57 years, and body mass index (BMI) > 21.57 kg/m2 were associated with better outcomes. While the diameter of radial artery, proximal radial artery close to the anastomosis, brachial artery, the flow volume of brachial artery, the length and peak velocity (PV) of the VVRS, and the diameter and PV after the VVRS had no association with the primary patency rate. After PTA, only patients with a diameter of VVRS > 4.0 mm had favorable outcome. In addition, patients with a gain of diameter of VVRS > 2.4 mm after PTA had a trend of better outcomes.

CONCLUSIONS

The diameter of VVRS before and after PTA could be served as markers to predict primary patency rate and second patency rate in AVF patients with VVRS. The gain of diameter of VVRS could also be a potential marker.

CLINICAL IMPACT

Using simple markers of sonographic parameters, we could quickly identify patients with a higher risk of restenosis. These patients should be followed more closely in case of restenosis at early. It is also beneficial to the prevention of thrombosis. These measures help to preserve more valuable vascular for a long-term dialysis. Additionally, the physician should pay more attention on the dialysis-related complications in these risky patients, such as hemodialysis-related hypotension.

Late creation of vascular access increased post-hemodialysis mortality, hospitalization, and health-care expenditure: A population-based cohort study in Taiwan

BACKGROUND/PURPOSE

The optimal timing of vascular access (VA) creation for hemodialysis (HD) and whether this timing affects mortality and health-care utilization after HD initiation remain unclear. Thus, we conducted a population-based study to explore their association.

METHODS

We used Taiwan's National Health Insurance Research Database to analyze health-care outcomes and utilization in a cohort initiating HD during 2003-2013. We stratified patients by the following VA creation time points: >180, 91-180, 31-90, and ≤30 days before and ≤30 days after HD initiation and examined all-cause mortality, ambulatory care utilization/costs, hospital admission/costs, and total expenditure within 2 years after HD. Cox regression, Poisson regression, and general linear regression were used to analyze mortality, health-care utilization, and costs respectively.

RESULTS

We identified 77,205 patients who started HD during 2003-2013. Compared with the patients undergoing VA surgery >180 days before HD initiation, those undergoing VA surgery ≤30 days before HD initiation had the highest mortality-15.92 deaths per 100-person-years, crude hazard ratio (HR) 1.56, and adjusted HR 1.28, the highest hospital admissions rates- 2.72 admission per person-year, crude rate ratio (RR) 1.48 and adjusted RR 1.32, and thus the highest health-care costs- US$31,390 per person-year, 7% increase of costs and 6% increase with adjustment within the 2-year follow-up after HD initiation.

CONCLUSION

Late VA creation for HD can increase all-cause mortality, hospitalization, and health-care costs within 2 years after HD initiation. Early preparation of VA has the potential to reduce post-HD mortality and healthcare expenses for the ESKD patients.

Controlled Delivery of Rosuvastatin or Rapamycin through Electrospun Bismuth Nanoparticle-Infused Perivascular Wraps Promotes Arteriovenous Fistula Maturation

In the context of arteriovenous fistula (AVF) failure, local delivery enables the release of higher concentrations of drugs that can suppress neointimal hyperplasia (NIH) while reducing systemic adverse effects. However, the radiolucency of polymeric delivery systems hinders long-term in vivo surveillance of safety and efficacy. We hypothesize that using a radiopaque perivascular wrap to deliver anti-NIH drugs could enhance AVF maturation. Through electrospinning, we fabricated multifunctional perivascular polycaprolactone (PCL) wraps loaded with bismuth nanoparticles (BiNPs) for enhanced radiologic visibility and drugs that can attenuate NIH─rosuvastatin (Rosu) and rapamycin (Rapa). The following groups were tested on the AVFs of a total of 24 Sprague-Dawley rats with induced chronic kidney disease: control (i.e., without wrap), PCL-Bi (i.e., wrap with BiNPs), PCL-Bi-Rosu, and PCL-Bi-Rapa. We found that BiNPs significantly improved the wraps' radiopacity without affecting biocompatibility. The drug release profiles of Rosu (hydrophilic drug) and Rapa (hydrophobic drug) differed significantly. Rosu demonstrated a burst release followed by gradual tapering over 8 weeks, while Rapa demonstrated a gradual release similar to that of the hydrophobic BiNPs. In vivo investigations revealed that both drug-loaded wraps can reduce vascular stenosis on ultrasonography and histomorphometry, as well as reduce [18F]Fluorodeoxyglucose uptake on positron emission tomography. Immunohistochemical studies revealed that PCL-Bi-Rosu primarily attenuated endothelial dysfunction and hypoxia in the neointimal layer, while PCL-Bi-Rapa modulated hypoxia, inflammation, and cellular proliferation across the whole outflow vein. In summary, the controlled delivery of drugs with different properties and mechanisms of action against NIH through a multifunctional, radiopaque perivascular wrap can improve imaging and histologic parameters of AVF maturation.

Rapid intervention team strategy improves intervention quality for patients undergoing hemodialysis with arteriovenous shunt dysfunction or failure

BACKGROUND

Vascular access dysfunction is a great burden for hemodialysis patients. Early intervention of a dysfunctional arteriovenous shunt is associated with higher technical success and may improve midterm patency. This trial aimed to estimate the feasibility of a new system, the "rapid intervention team" (RIT) strategy.

METHODS

We recruited hemodialysis patients who visited our hospital because of arteriovenous shunt dysfunction or failure to undergo an RIT strategy from September 1, 2019 to December 31, 2022. In addition, we included a control group comprising patients who underwent percutaneous intervention for arteriovenous shunt dysfunction or failure before this strategy was implemented from February 1, 2017 to December 31, 2022. Case number, time to intervention, all-cause mortality, cumulative survival rate, and number of patients who required temporary dialysis catheter insertion and recreation were compared between the two groups. The primary endpoints were double-lumen insertion, a composite outcome involving permanent catheter insertion, and the need for recreation. The secondary endpoint was all-cause mortality.

RESULTS

We enrolled 1054 patients, including 544 (51.6%) and 510 (48.4%) in the RIT and control groups, respectively. Even with the coronavirus disease of 2019 (COVID-19) pandemic, the number of cases significantly increased after the implementation of the RIT strategy (from 216 in 2019 to 828 in 2022, p for trend <0.001). The RIT group had a shortened time to intervention ( p for trend <0.001). The implementation of the RIT strategy was significantly associated with a reduced risk of insertion of a temporary double-lumen catheter and recreation of vascular access (1% vs 6% and 1% vs 28%, respectively; both p < 0.01). The cumulative survival rate was not significantly different between the RIT and control groups ( p = 0.16).

CONCLUSION

The implementation of the RIT strategy improves the quantity and quality of percutaneous transluminal intervention for arteriovenous shunt dysfunction or failure in patients undergoing hemodialysis.

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.

Cost-effectiveness analysis of endovascular vs surgical arteriovenous fistula creation in the United States

OBJECTIVE

In the United States, an estimated $2.8 billion annually is spent on vascular access and its complications. Endovascular arteriovenous fistula (endoAVF) creation is a novel, minimally invasive alternative to traditional surgical AV fistula (sAVF) creation in ≤60% of patients. Although cost effective in single-payer systems, the clinical and financial impact of endoAVF in the United States remains uncertain.

METHODS

We constructed a decision tree followed by a probabilistic cohort state-transition model to study the cost effectiveness of endoAVF vs sAVF creation. We conducted a systematic review to obtain input parameters including technical success, maturation, patency, and utility values. We derived costs from the Medicare 2022 fee schedule and from the literature. We used a 5-year time horizon, an annual discount rate of 3% for costs and utilities (measured in quality-adjusted life-years [QALYs]), and the common willingness-to-pay threshold of $50,000. One-way and Monte Carlo probabilistic sensitivity analyses were performed varying technical success, patency, reintervention, cost, and utility parameters.

RESULTS

In the base-case scenario, endoAVF ($30,129 average per-person costs, 2.19 QALYs gained, 65% patent at 5 years) was not cost effective compared with sAVF ($12.987 average per-person costs, 2.11 QALYs gained, 66% patent at 5 years), generating an incremental cost-effectiveness ratio of $227,504 per QALY gained. In one-way sensitivity analyses, endoAVF becomes cost effective when the initial cost of sAVF creation exceeds endoAVF by ≥$600 (eg, if endoAVF creation costs ≤$3000 relative to the base-case sAVF cost of $3600), the additional QALYs gained from endoAVF exceeds 0.12 QALYs/year (eg, 0.81 QALYs gained/year from endoAVF compared with base-case sAVF 0.69 QALYs/year), the endoAVF maturation rate is >90% (base case 78%), or the sAVF maturation rate is <65% (base case 78%). Probabilistic sensitivity analysis demonstrated that sAVF remained the optimal strategy in 71% of iterations.

CONCLUSIONS

EndoAVF is not cost effective compared with sAVF when modeling 5-year outcomes. The main driver of sAVF remaining cost effective is the four times higher up-front cost for endoAVF creation, as well as a relatively low additional increase in quality of life for endoAVF. It will be important to establish how the endoAVF learning curve contributes to upfront costs and, given the annual cost attributed to vascular access nationally, a randomized controlled trial is warranted.

Long-term results of autologous scaffold-free tissue-engineered vascular graft for hemodialysis access

BACKGROUND

The growing size of the end stage renal disease (ESRD) population highlights the need for effective dialysis access. Exhausted native vascular access options have led to increased use of catheters and prosthetic shunts, which are both associated with high risks of access failure and infection. Emerging alternatives include tissue-engineered vascular grafts (TEVG). Here we present the endpoint results for 10 ESRD patients with the scaffold-free tissue-engineered vascular access produced from sheets of extracellular matrix produced in vitro by human cells in culture.

METHODS

Grafts were implanted as arteriovenous shunts in 10 ESRD patients with a complex history of access failure. Follow-up included ultrasound control of graft morphology and function, dialysis efficiency, access failure, intervention rate, as well as immunohistochemical analysis of graft structure.

RESULTS

One patient died of unrelated causes and three shunts failed to become useable access grafts during the 3-month maturation phase. The 12-month primary and secondary patency for the other six shunts was 86%. Survival of six shunts functioning as the vascular access was 22 ± 12 months with longest primary patency of 38.6 months. The dialysis event rate of 3.34 per patient-year decreased significantly with the use of this TEVG to 0.67.

CONCLUSIONS

This living autologous tissue-engineered vascular graft seems to be an alternative to synthetic vascular access options, exhibiting advantages of native arteriovenous fistula.

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.

Increased expression of the P2Y12 receptor is involved in the failure of autogenous arteriovenous fistula caused by stenosis

OBJECTIVE

This study investigated the role of the P2Y12 receptor in autogenous arteriovenous fistula (AVF) failure resulting from stenosis.

METHODS

Stenotic venous tissues and blood samples were obtained from patients with end-stage renal disease (ESRD) together with AVF stenosis, while venous tissues and blood samples were collected from patients with ESRD undergoing initial AVF surgery as controls. Immunohistochemistry and/or immunofluorescence techniques were utilized to assess the expression of P2Y12, transforming growth factor-β1 (TGF-β1), monocyte chemotactic protein 1 (MCP-1), and CD68 in the venous tissues. The expression levels of P2Y12, TGFβ1, and MCP-1 were quantified using quantitative reverse transcription-polymerase chain reaction and western blot analyses. Double and triple immunofluorescence staining was performed to precisely localize the cellular localization of P2Y12 expression.

RESULTS

Expression levels of P2Y12, TGFβ1, MCP-1, and CD68 were significantly higher in stenotic AVF venous tissues than in the control group tissues. Double and triple immunofluorescence staining of stenotic AVF venous tissues indicated that P2Y12 was predominantly expressed in α-SMA-positive vascular smooth muscle cells (VSMCs) and, to a lesser extent, in CD68-positive macrophages, with limited expression in CD31-positive endothelial cells. Moreover, a subset of macrophage-like VSMCs expressing P2Y12 were observed in both stenotic AVF venous tissues and control venous tissues. Additionally, a higher number of P2Y12+/TGF-β1+ double-positive cells were identified in stenotic AVF venous tissues than in the control group tissues.

CONCLUSION

Increased expression of P2Y12 in stenotic AVF venous tissues of patients with ESRD suggests its potential involvement in the pathogenesis of venous stenosis within AVFs.

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.

Automated 3D ultrasound enables novice users to measure arteriovenous fistula maturation parameters with comparable accuracy to conventional duplex by trained sonographers: Results of a benchtop study

BACKGROUND

Arteriovenous fistulae (AVF) are considered the preferred hemodialysis access but up to 50% of all AVF created in the United States never mature. Doppler ultrasound (DUS) is useful for predicting fistula maturity and impending fistula failure. DUS is resource-intensive and is associated with poor compliance rates in dialysis patients, ranging from 12% to 33%.

METHODS

EchoSure is an FDA-cleared 3D Doppler ultrasound device that automatically delivers quantitative blood flow and anatomic vascular information. The technology can be used at the bedside by personnel without formal sonographic training, nullifying limitations of traditional Duplex ultrasound imaging. This study compared the EchoSure system in the hands of inexpert personnel to a traditional expert-operated DUS for rapid assessment of a benchtop model vascular system with flow, diameter, and depth expected in a human AVF.

RESULTS

Both Duplex and EchoSure performed within the expected tolerance of ultrasound readings (35%) for volume flow, with the average error (AE) between the observed measurement and the ground truth being 8% for Duplex and 8% for EchoSure. However, the average coefficient of variation (CV) for Duplex pooled over all flow rate measurements was 17% versus 4% for EchoSure. Regarding diameter, Duplex measurements had AE of 15% with an average CV of 6% across all measurements versus EchoSure AE of 4% and average CV of 2%. Duplex and EchoSure measurements over all depths had the same AE of 2%. The two modalities were not statistically different for depth measurement (p = 0.05) but EchoSure measured closer to the ground truth for flow rate and vessel diameter (flow: p = 0.028, ρ = -0.07; diameter: p < 0.001, ρ = 0.69). The inexpert personnel using EchoSure acquired data 62% faster than the expert sonographers using the Duplex ultrasound (141 min for Duplex vs 87 min for EchoSure).

CONCLUSIONS

EchoSure may offer an accurate and convenient alternative for imaging fistulas in the clinic.

Cost-Effectiveness of Drug-Coated Balloon Angioplasty versus Plain Old Balloon Angioplasty for Arteriovenous Fistula Stenosis

OBJECTIVE

To compare the cost-effectiveness of drug-coated balloon angioplasty (DCB) versus plain old balloon angioplasty (POBA) for treatment of arteriovenous fistula (AVF) stenosis.

METHODS

A Markov model was created to compare DCB versus POBA for AVF stenosis over a 2-year time horizon from a United States payer's perspective. Probabilities related to complications, restenosis, retreatment, and all-cause mortality were obtained from published literature. Costs were calculated using Medicare reimbursement rates and data from published cost analyses, inflation-adjusted to 2021. Health outcomes were measured with quality-adjusted life years (QALY). Probabilistic and deterministic sensitivity analyses were performed with a willingness-to-pay threshold of $100,000/QALY.

RESULTS

Base case calculation showed better quality-of-life outcomes but increased cost with POBA compared to DCB, with an incremental cost-effectiveness ratio of $27,413/QALY, making POBA the more cost-effective strategy in the base case model. Sensitivity analyses showed that DCB becomes cost-effective if the 24-month mortality rate after DCB is no more than 3.4% higher than that after POBA. In secondary analyses where mortality rates were equalized, DCB was more cost-effective than POBA until its additional cost reached more than $4213 per intervention.

CONCLUSION

When modeled from a payer's perspective over 2 years, the cost utility of DCB versus POBA varies with mortality outcomes. POBA is cost-effective if 2-year all-cause mortality after DCB is greater than 3.4% higher than after POBA. If 2-year mortality after DCB is less than 3.4% higher than after POBA, DCB is cost-effective until its additional cost per procedure exceeds $4213 more than POBA.

LEVEL OF EVIDENCE IV

HISTORICALLY CONTROLLED STUDY.: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Rethinking an effective AV fistula-graft screening program. An "A B C"

The goal of a vascular access screening program is to detect and preemptively correct hemodynamically significant stenosis, however, a practice pattern allowing to implement such a program still remains to be defined. Achieving balance between the increase in access-related procedures by adopting an aggressive screening program, and the risks associated with the absence of any screening program, i.e., failure or abandonment of the arterio-venous access with need for central venous catheter placement, can be extremely challenging. All major guidelines agree about the role of arterio-venous access monitoring, but the way surveillance should be managed is still a controversial issue. Preserving long-term vascular access function should be a goal for all hemodialysis teams, yet it ideally requires a multidisciplinary effort with a monitoring program, calling for a great deal of involvement by hemodialysis health professionals. In this context, the engagement of skilled nurses and the role of patient empowerment with collaborative decision-making may be the key to a successful vascular access screening program. Screening programs should be personalized, shared with the patients, and tailored according to vascular access type and site. In the near future, new devices and the use of artificial intelligence may allow to support interpretation of complex data and lead to the development of prediction models for vascular access failure.

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.

Deep learning analysis of blood flow sounds to detect arteriovenous fistula stenosis

For hemodialysis patients, arteriovenous fistula (AVF) patency determines whether adequate hemofiltration can be achieved, and directly influences clinical outcomes. Here, we report the development and performance of a deep learning model for automated AVF stenosis screening based on the sound of AVF blood flow using supervised learning with data validated by ultrasound. We demonstrate the importance of contextualizing the sound with location metadata as the characteristics of the blood flow sound varies significantly along the AVF. We found the best model to be a vision transformer trained on spectrogram images. Our model can screen for stenosis at a performance level comparable to that of a nephrologist performing a physical exam, but with the advantage of being automated and scalable. In a high-volume, resource-limited clinical setting, automated AVF stenosis screening can help ensure patient safety via early detection of at-risk vascular access, streamline the dialysis workflow, and serve as a patient-facing tool to allow for at-home, self-screening.

Maintenance and Salvage of Hemodialysis Access

Many end-stage kidney failure patients require hemodialysis as a life-sustaining treatment. Hemodialysis access via arteriovenous fistula or graft creation is preferred over long-term dialysis catheters, but intervention to maintain patency and prevent access failure is common. Endovascular and open surgical techniques are both utilized to address the underlying etiology of failure. Endovascular options include balloon angioplasty, angioplasty with stenting, and drug-eluting stents. Open revision is commonly needed for recurrent stenosis, aneurysmal or pseudoaneurysmal change, hemodialysis access-induced distal ischemia, and infection. Treatment plans should be guided by patient's individualized goals of care and require a multidisciplinary approach to the management of this complex disease.

Development of open-source software for free-hand 3D vascular ultrasound: Dialysis fistula application

BACKGROUND

The arteriovenous fistula (AVF) is the preferred vascular access for End Stage Renal Disease, having superior patency and lower infection risks than prosthetic graft and catheter access. When AVF dysfunction or delayed maturation does occur, the gold standard for diagnosis is the fistula angiogram (a.k.a. fistulogram). 3D ultrasound is available for obstetrical and other specialized uses, but it is cost prohibitive and has a field of view that is too small to cover the region of interest for the dialysis fistula application. We sought to develop a point of care 3D solution using freehand 2D ultrasound data acquisition.

METHODS

We developed open-source software for 3D image reconstruction and projection of an angiogram-like image of the vascular access using a 2D freehand ultrasound scanner. We evaluated this software by comparing the ultrasound "sono-angiogram" images to fistulogram images in five subjects, using visual inspection and by applying the Percent of Exact Match (PEM) as a statistic test.

RESULTS

The sono-angiograms showed identifiable characteristics that matched the fistulogram results in all five subjects. The PEM ranged between 42.8% and 77.0%, with Doppler and grayscale ultrasound data, showing complementary advantages and disadvantages when used for sono-angiogram image construction. Motion from freehand ultrasound acquisition was a significant source of mismatch. 3D image generation is a potential advantage with ultrasound data.

CONCLUSIONS

While further work is needed to improve the accuracy with free hand scanning, fistulogram-like "sono-angiograms" can be generated using point of care 2D ultrasound. Methods such as these may be able to assist in point-of-care diagnosis in the future. The software is open-source, and importantly, the ultrasound data used are non-proprietary and available from any standard ultrasound machine. The simplicity and accessibility of this approach warrant further study.

Osteopontin is a key regulator of vascular smooth muscle cell proliferation in the outflow vein of arteriovenous fistulas

OBJECTIVES

Despite advances in the maintenance of arteriovenous fistulas (AVFs), the patency rates remain suboptimal. Most AVFs fail due to outflow vein stenosis; however, the underlying mechanism of AVF stenosis remains unclear. The present study aimed to identify key factors associated with AVF outflow stenosis.

METHODS

We obtained gene expression profiling data for the outflow vein of AVF from three Gene Expression Omnibus database datasets (GSE39488, GSE97377, and GSE116268) and analyzed the common differentially expressed genes (DEGs). We evaluated a common DEG in an aortocaval mouse model and the stenotic outflow veins of AVFs collected from patients. Furthermore, we isolated vascular smooth muscle cells (VSMCs) from the inferior vena cava (IVC) of wild-type (WT) and osteopontin (Opn)-knockout (KO) mice and assessed the proliferation of VSMCs following stimulation with platelet-derived growth factors (PDGFs).

RESULTS

OPN was the only common upregulated DEG among all datasets. OPN was expressed in the medial layer of the outflow vein of AVF in aortocaval mouse models and co-stained with the VSMC marker (α-smooth muscle actin). OPN expression was markedly increased in the VSMCs of stenotic outflow veins of AVF collected from patients undergoing hemodialysis compared to presurgical veins acquired during AVF formation surgery. PDGF-induced VSMC proliferation was significantly increased in the VSMCs isolated from the IVC of WT mice but not in those isolated from the IVC of Opn-KO mice.

CONCLUSIONS

OPN may be a key gene involved in VSMC proliferation in the AVF outflow veins and a therapeutic target to improve the AVF patency rate.

Polycladia myrica-based delivery of selenium nanoparticles in combination with radiotherapy induces potent in vitro antiviral and in vivo anticancer activities against Ehrlich ascites tumor

Background: Over the last few decades, nanotechnology has entered daily life through various applications, therefore, there has been a trend toward developing new approaches to green-mediated nanotechnology that encourage nanomaterial formation through biological methods such as plants or microorganisms. Algae have gained increasing attention from nanotechnology scientists and have paved the way for the emergence of "algae nanotechnology" as a promising field. Methods: Via using the aqueous extract of the brown alga Polycladia myrica, selenium nanoparticles were synthesized and characterized by using seven instruments: SEM, TEM, UV spectra, Zeta potential, EDX, X-ray diffraction, and FTIR. P. myrica selenium nanoparticles (PoSeNPs) were then examined for their antiviral activity against HSV-1 (Herpes simplex I) and anticancer against human colon cancer cell line (HCT-116) in vitro and in vivo alone and in combination with laser therapy of power 2 mW against Ehrlich carcinoma (EAC). Results: PoSeNPs ranging between 17.48 nm and 23.01 nm in size, and EDX revealed the selenium mass and its atoms as 0.46% ± 0.07% and 0.08% ± 0.01% respectively. Their anticancer potentiality in vitro was with maximum inhibitions of 80.57% and 73% and IC50 = 14.86 μg/mL and 50 mg/mL against HCT-116 and EAC cell lines respectively, while their in vivo alone and in combination with laser therapy of power 2 mW showed a potent therapy effect against Ehrlich ascites carcinoma (EAC). Conclusion: This study concluded that PoSeNPs do not have a toxic effect; they exhibit high effectiveness as a photothermal agent for cancer therapy, with promising applications in future biomedical fields. The combined therapy showed a significant decrease in tumor volume, massive tumor cell necrosis, shrinking, and disappearance. It also showed improvement in liver TEM, histology, kidney function: urea and creatinine, and liver enzymes: ALT, and AST.

Association of Four Types of Vascular Access Including Arterial Superficialization with Mortality in Maintenance Hemodialysis Patients: A Nationwide Cohort Study in Japan

INTRODUCTION

Vascular access usage varies widely across countries. Previous studies have evaluated the association of clinical outcomes with the three types of vascular access, namely, arteriovenous fistula (AVF), arteriovenous graft (AVG), and tunneled and cuffed central venous catheter (TC-CVC). However, little is known regarding the association between arterial superficialization (AS) and the mortality of patients.

METHODS

A nationwide cohort study was conducted using data from the Japanese Society for Dialysis Therapy Renal Data Registry (2006-2007). We included patients aged ≥20 years undergoing hemodialysis with a dialysis vintage ≥6 months. The exposures of interest were the four types of vascular access: AVF, AVG, AS, and TC-CVC. Cox proportional hazard models were used to evaluate the associations of vascular access types with 1-year all-cause and cause-specific mortality.

RESULTS

A total of 183,490 maintenance hemodialysis patients were included: 90.7% with AVF, 6.9% with AVG, 2.0% with AS, and 0.4% with TC-CVC. During the 1-year follow-up period, 13,798 patients died. Compared to patients with AVF, those with AVG, AS, and TC-CVC had a significantly higher risk of all-cause mortality after adjustment for confounding factors: adjusted hazard ratios (95% confidence intervals) - 1.30 (1.20-1.41), 1.56 (1.39-1.76), and 2.15 (1.77-2.61), respectively. Similar results were obtained for infection-related and cardiovascular mortality.

CONCLUSION

This nationwide cohort study conducted in Japan suggested that AVF usage may have the lowest risk of all-cause mortality. The study also suggested that the usage of AS may be associated with better survival rates compared to those of TC-CVC in patients who are not suitable for AVF or AVG.

CMS ESRD quality incentive program has not improved patient dialysis vascular access

PURPOSE

Over 468,000 patients in the United States use hemodialysis to manage End Stage Renal Disease (ESRD). The purpose of this study was to determine whether the dialysis access Clinical Performance Measures (CPMs) of Centers for Medicare & Medicaid Services (CMS) ESRD Quality Incentive Program (QIP) have increased arteriovenous fistula (AVF) rates and decreased long-term tunneled hemodialysis catheter (TDC) rates among hemodialysis patients in United States.

METHODS

Retrospective observational study: evaluated reported AVF and long-term TDC rates of 4804 dialysis facilities which reported dialysis access data as part of the ESRD QIP from Payment Year (PY) 2014-2020. Facilities were also sorted by specific additional criteria to examine disparities in dialysis access.

RESULTS

Mean AVF rates of included facilities increased from 63.7% in PY 2014 to 67.2% in PY 2016 (p < 0.05), did not change in PY 2017 (p > 0.05), and declined significantly in PY 2018-2020 to 64.1% in PY 2020, near AVF rates at the inception of program. Long-term TDC rates decreased from 10.4% in PY 2014 to 9.88% in PY 2015 (p < 0.05), then increased in PY 2015-PY 2020 to rates higher than at the inception of program, at 11.8% in PY 2020 (p < 0.05). Facilities serving majority Black ZIP Code Tabulation Areas (ZCTAs) or ZCTAs with median income <$45,000 achieved significantly lower AVF rates (p < 0.05) with no significant difference in long-term TDC rates (p > 0.05). AVF rates correlated positively and long-term TDC rates correlated negatively with star rating of facilities (p < 0.05).

CONCLUSION

As one of the first financial QIPs in healthcare, the ESRD QIP has not achieved the stated goals of the CMS to increase AVF access rates above 68% and reduce long-term TDC clinical rates below 10%. Systemic disparities in race, geographic region, economic status, healthcare access, and education of providers and patients prevent successful attainment of goal metrics.

Efficacy of blood flow measurement using intraoperative color flow Doppler ultrasound as a predictor of autologous arteriovenous fistula maturation

INTRODUCTION

Hemodialysis vascular access parameters of intraoperative Color flow Doppler ultrasound remain controversial. This study aimed to evaluate the optimal cut-off value and efficacy of intraoperative arteriovenous fistula parameters identified by Color flow Doppler ultrasound for arteriovenous fistula maturation success.

METHODS

This retrospective study consisted of a review of the medical records of 137 consecutive patients who underwent their first autologous arteriovenous fistula formation under local anesthesia for end-stage renal disease from April 9, 2020 to March 19, 2021.

RESULTS

The receiver operating characteristic curve analysis revealed that the optimal cut-off for intraoperative cephalic vein flow volume for brachiocephalic arteriovenous fistula maturation at the 4-week follow-up was 349.53 ml/min (area under the curve, 0.792; p, 0.036; Youden index, 0.514).

CONCLUSION

Intraoperative color Doppler ultrasound outflow cephalic vein flow volume is a useful factor in predicting arteriovenous fistula maturation. Intraoperative Color flow Doppler ultrasound should be performed.

The role of stents in hemodialysis vascular access

Vascular access is the Achilles' heel of dialysis therapy among patient with end stage kidney disease. The development of neointimal hyperplasia and subsequent stenosis is common in vascular access and is associated with significant morbidity. Percutaneous transluminal angioplasty using balloon inflation was the standard therapy of these lesions. However, the balloon-based approaches were associated with poor vascular access patency rate necessitating new inventions. It is within this context that different types of stents were developed in order to improve the overall dialysis vascular access functionality. In this article, we review the available literature regarding the use of stents in treating dialysis vascular access stenotic lesions. Further, we review the major clinical trials of stent use in different anatomic locations and in different clinical scenarios.

Conservative management of a lymphocele that formed shortly after creation of an arteriovenous fistula for hemodialysis

Patients with end-stage renal disease require to establish vascular access for regular hemodialysis. The creation of arteriovenous fistula (AVF) is usually a safe procedure; however, there could be complications such as bleeding, hematoma, pseudoaneurysm, thrombosis, infection, and steal syndrome. A rare complication of such vascular manipulation could be formation of lymphocele. We present a case of a 67-year-old man who presented with a progressively enlarging mass 12 days after the surgery for AVF creation at the site of surgery in the right upper arm. Ultrasonographic examination revealed a fluid-filled cystic structure measuring about 4.2 × 3.6 × 1.9 cm under the skin just above the anastomosis. The fluid was aspirated using ultrasound-guided fluoroscopy that relieved the swelling. The analysis of aspirate suggested the cyst to be a lymphocele. The mass re-enlarged to its previous size in the next 3 days. While under observation for signs of complication, regular intermittent compression and a low-fat diet completely resolved the lymphocele over the subsequent 3 months. The less common occurrence of such lymphocele post AVF creation needs to be evaluated for its potential for complication, in the absence of which the lymphocele is amenable to conservative management using regular intermittent compression and low-fat oral diet.

Hemodialysis Access Type and Access Patency Loss: An Observational Cohort Study

Rationale & Objective

Access patency outcomes for arteriovenous fistulas (AVFs) as compared with arteriovenous grafts (AVGs) in patients receiving hemodialysis (HD) who have achieved a functioning permanent access are not fully explored.

Study Design

Observational cohort study.

Setting & Population

Fee-for-service Medicare beneficiaries aged ≥18 years with kidney failure who were newly using a permanent access for maintenance HD from the United States Renal Data System (2010-2015). Patients using an oral anticoagulant were excluded.

Exposure

AVG or AVF.

Outcomes

Loss of primary unassisted, primary assisted, and secondary patency.

Analytical Approach

Outcomes were characterized using cumulative incidence curves, and HRs adjusted for sociodemographic and clinical factors were estimated for the comparison of AVF versus AVG.

Results

The cohort included 60,329 and 17,763 patients newly using an AVF and AVG, respectively, for HD. Over 3 years of follow-up, AVG users, compared to AVF users, had a higher cumulative incidence of loss of primary unassisted patency (87% vs 69%; HR, 1.56; 95% CI, 1.52-1.60), loss of primary assisted patency (69% vs 25%; HR, 3.79; 95% CI, 3.67-3.92), and loss of secondary patency (22% vs 10%; HR, 2.03; 95% CI, 1.92-2.16). Stratified analyses revealed differences by subgroups; in particular, incidence of patency loss was higher among patients who underwent prior interventions to maintain prefunctional access patency and Black patients.

Limitations

This analysis focused on outcomes occurring after first successful use of a permanent access and thus does not inform about risk of patency loss during access maturation.

Conclusions

Among patients with kidney failure who successfully used a permanent access for HD, patency loss was consistently substantially higher in those using AVGs compared with AVFs. New interventions, such as prophylactic drugs, are needed to improve access longevity and reduce the need for invasive interventions, particularly among patients unable to receive a fistula.

Bindarit encapsulated nanoparticles prevent venous neointimal hyperplasia and restenosis in a murine angioplasty model

Monocyte and macrophage recruitment occur to the injured vessel wall after percutaneous transluminal angioplasty (PTA) of stenotic arteriovenous fistulas (AVF) through increased expression of MCP-1 leading to venous neointimal hyperplasia (VNH) and venous stenosis (VS). We hypothesized that adventitial delivery of Bindarit, an oral selective inhibitor of MCP-1, -2, and -3 encapsulated in poly lactic-co-glycolic acid (PLGA) nanoparticles embedded in a thermosensitive Pluronic F127 hydrogel (BN NP) could prevent VNH/VS formation in a murine model of PTA with AVF. Scanning electron microscope and dynamic light scattering were used to characterize the BN NP and control nanoparticles (NP C). Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to study drug release kinetics. Immediately after PTA, in a murine model of AVF stenosis, BN NP or NP C was administrated to the adventitia of outflow veins. Animals were sacrificed 3 and 21 days later for gene expression, histomorphometric, and immunohistochemical analyses. Doppler ultrasound was performed weekly. There was no difference in the size and storage modulus of BN NP compared to controls. The pharmacokinetic analysis demonstrated increased drug release from BN NP when compared to controls. BN NP-treated vessels had reduced MCP-1, MCP-2, and MCP-3 gene, and protein levels, reduced macrophage/monocyte abundance, proinflammatory cytokines, and venous fibrosis resulting in positive vascular remodeling and improved patency with reduced VNH/VS. There was increased peak velocity 21 days after PTA in the BN NP group. Adventitial administration of BN NP to the outflow vein after PTA results in decreased VNH/VS.

Association between anaesthesia type and arteriovenous fistula maturation

BACKGROUND

Whereas general anaesthesia is commonly used for haemodialysis fistula creation, regional or local anaesthesia has been posited to lead to better fistula maturation outcomes. We sought to measure the association between anaesthesia type and arteriovenous fistula maturation.

METHODS

We performed a secondary analysis of data from the Hemodialysis Fistula Maturation study, a multicentre prospective cohort study of advanced chronic kidney disease patients who underwent single-stage upper extremity fistula creation between 2010 and 2013. We evaluated the relationship between anaesthesia type and unassisted (without maturation-facilitating interventions) or overall (unassisted or assisted) fistula maturation using multivariable logistic regression.

RESULTS

Among 602 participants, 336 (55.8%) received regional/local anaesthesia and 266 (44.2%) received general anaesthesia. Unassisted maturation occurred in 164/309 patients (53.1%) after regional/local vs 91/226 patients (40.3%) after general anaesthesia (P=0.003). After adjustment for patient factors and fistula type, regional/local anaesthesia was associated with greater odds of unassisted maturation than general anaesthesia (odds ratio 1.72, 95% confidence interval 1.24-2.39; P=0.001). However, after further adjustment for clinical centre fixed effects, odds of unassisted maturation did not differ by anaesthesia type (odds ratio 1.03, 95% confidence interval 0.78-1.36; P=0.830). Similar findings were observed for overall maturation and composite endpoints accounting for potential survivorship bias.

CONCLUSIONS

Regional/local anaesthesia was associated with increased odds of fistula maturation when adjusting for patient factors and fistula type. However, this association did not persist after adjusting for centre fixed effects. Future research is needed to better understand the relationship between anaesthesia type and centre factors to optimise outcomes after fistula surgery.

Association of Frailty With Thrombosis of Hemodialysis Vascular Access: A Prospective Taiwanese Cohort Study

RATIONALE & OBJECTIVE

Frailty, a multidimensional construct, has been associated with poor outcomes in patients receiving maintenance dialysis. This study assessed the association of frailty with dialysis vascular access patency.

STUDY DESIGN

Multicenter prospective cohort study.

SETTING & PARTICIPANTS

761 prevalent patients receiving hemodialysis at 9 centers in Taiwan as of January 2018.

EXPOSURE

Performance-based frailty was defined as 3 of the following: unintentional weight loss, weakness, exhaustion, low physical activity, and slow gait speed. Patients were categorized as prefrail if they had 1 or 2 of these characteristics.

OUTCOME

Rate of and time to dialysis access thrombosis. Data regarding vascular access events were collected for 30 months after enrollment through December 31, 2020.

ANALYTICAL APPROACH

Logistic regression analysis was used to estimate the association of clinical characteristics with frailty. Cox proportional hazards regression analysis was used to estimate the association of frailty with vascular access thrombosis adjusted for known clinical risk factors.

RESULTS

The patients' mean age was 66 years, 46% were female, 18% had synthetic graft accesses, and 82% arteriovenous fistulas. Overall, 31% were frail, 35% were prefrail, and 34% were not frail. The frailty phenotype was associated with age, female sex, low body mass index, diabetes mellitus, and prior stroke. During a median follow-up of 731 days, 161 patients (21%) had access thrombosis events (not frail, 14%; prefrail, 20%; frail, 30%; P < 0.001). Frail patients had a higher risk of vascular access thrombosis than nonfrail patients (HR, 2.31 [95% CI, 1.55-3.39], P < 0.001). After multivariable adjustment for age and comorbidities, frailty remained significantly associated with access thrombosis for both fistulas and grafts.

LIMITATIONS

Limited generalizability and potential residual confounding.

CONCLUSIONS

Frailty is associated with an increased risk of vascular access thrombosis. These findings highlight the risks of access failure experienced by frail patients receiving hemodialysis.

IN.PACT AV Access Trial: Economic Evaluation of Drug-Coated Balloon Treatment for Dysfunctional Arteriovenous Fistulae Based on 12-Month Clinical Outcomes

PURPOSE

To study, from a U.S. payer's perspective, the economic consequences of drug-coated balloon (DCB) versus standard percutaneous transluminal angioplasty (PTA) use for the treatment of stenotic lesions in dysfunctional hemodialysis arteriovenous fistulae.

MATERIALS AND METHODS

Cost differences between DCBs and PTA at year 1 and beyond were calculated via 2 methods. The first approach used the mean absolute number of trial-observed access circuit reinterventions through 12 months (0.65 ± 1.05 vs 1.05 ± 1.18 events per patient for DCBs and PTA, respectively) and projected treatment outcomes to 3 years. The second approach was based on the trial-observed access circuit primary patency rates at 12 months (53.8% vs 32.4%) and calculated the cost difference on the basis of previously published Medicare cost for patients who maintained or did not maintain primary patency. Assumptions regarding DCB device prices were tested in sensitivity analyses, and the numbers needed to treat were calculated.

RESULTS

Using the absolute number of access circuit reinterventions approach, the DCB strategy resulted in an estimated per-patient savings of $1,632 at 1 year and $4,263 at 3 years before considering the DCB device cost. The access circuit primary patency approach was associated with a per-patient cost savings of $2,152 at 1 year and $3,894 at 2.5 years of follow-up. At the theoretical DCB device reimbursement of $1,800, savings were $1,680 and $2,049 at 2.5 and 3 years, respectively. The one-year NNT of DCB compared to PTA was 2.48.

CONCLUSIONS

Endovascular therapy for arteriovenous access stenosis with the IN.PACT AV DCB can be expected to be cost-saving if longer follow-up data confirm its clinical effectiveness.