An analysis of vascular access thrombosis events from the Proactive IV Iron Therapy in Hemodialysis Patients (PIVOTAL) trial

Introduction

Treatment of anemia in dialysis patients has been associated with increased risk of vascular access thrombosis (VAT). Proactive IV irOn Therapy in hemodiALysis Patients (PIVOTAL) was a clinical trial of proactive compared with reactive i.v. iron therapy in patients requiring hemodialysis. We analyzed the trial data to determine whether randomized treatment arm, alongside other clinical and laboratory variables, independently associated with VAT.

Methods

In PIVOTAL, 2141 adult patients were randomized. The type of vascular access (arteriovenous fistula [AVF], arteriovenous graft [AVG], or central venous catheter [CVC]) was recorded at baseline and every month after randomization. The associations between clinical and laboratory data and first VAT were evaluated in a multivariate analysis.

Results

A total of 480 (22.4%) participants experienced VAT in a median of 2.1 years of follow-up. In multivariable analyses, treatment arm (proactive vs. reactive) was not an independent predictor of VAT (hazard ratio [HR] 1.13, P = 0.18). Diabetic kidney disease (HR 1.45, P < 0.001), AVG use (HR 2.29, P < 0.001), digoxin use (HR 2.48, P < 0.001), diuretic use (HR 1.25, P = 0.02), female sex (HR 1.33, P = 0.002), and previous/current smoker (HR 1.47, P = 0.004) were independently associated with a higher risk of VAT. Angiotensin receptor blocker (ARB) use (HR 0.66, P = 0.01) was independently associated with a lower risk of VAT.

Conclusion

In PIVOTAL, VAT occurred in nearly 1 quarter of participants in a median of just >2 years. In this post hoc analysis, randomization to proactive i.v. iron treatment arms did not increase the risk of VAT.

New Devices and Technologies for Hemodialysis Vascular Access: A Review

In the United States, hemodialysis remains the most common treatment modality for kidney failure, chosen by almost 90% of incident patients. A functioning vascular access is key to providing adequate hemodialysis therapy. Recently, major innovations in devices and technology for hemodialysis vascular access care have rapidly changed the landscape. Novel endovascular devices for creation of arteriovenous fistulas may offer a solution to the barriers encountered in initiating maintenance hemodialysis with a permanent vascular access rather than a central venous catheter (CVC). Furthermore, in the prevalent hemodialysis population, the minimally invasive endovascular arteriovenous fistula procedure should help improve long wait times for vascular access creation, which remains a major barrier to reducing CVC dependence. Bioengineered grafts are being developed and may offer another option to polytetrafluoroethylene grafts. Early studies with these biocompatible grafts are promising, as additional studies continue to evaluate their clinical outcomes in comparison to cryopreserved or synthetic options. Prolonging the vascular access patency with appropriate use of devices such as drug-coated balloons and stent grafts may complement the novel techniques of creating arteriovenous access. Finally, innovative solutions to treat stenosed and occluded thoracic central veins can provide an approach to creating a vascular access and allow patients with exhausted vasculature to remain on hemodialysis. The robust developments in hemodialysis vascular access are likely to change practice patterns in the near future.

KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease "Life-Plan" and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Association between Severe Anemia and Outcomes of Hemodialysis Vascular Access

BACKGROUND

The vast majority of patients undergoing hemodialysis (HD) are anemic. The severity of anemia in these patients may influence the postoperative outcomes and the durability of vascular access. Thus, the purpose of this study is to assess the association between anemia and adverse outcomes in patients undergoing HD access placement (arteriovenous grafts and fistula).

METHODS

Patients with chronic kidney disease stages IV and V recorded in the Vascular Quality Initiative Hemodialysis database between 2011 and 2017 were included. Patients were divided into 3 study groups based on preoperative hemoglobin (Hgb) levels: normal/mild anemia (Hgb: females ≥10 g/dL, males ≥12 g/dL), moderate anemia (Hgb: females: 7-9.9 g/dL, males: 9-11.9 g/dL), and severe anemia (Hgb: females<7 g/dL, males<9 g/dL). Multivariable logistic and Cox regression analyses were implemented to evaluate the association between anemia and 30-day mortality and primary patency (PP) at 1 year.

RESULTS

A total of 28,000 patients undergoing HD access surgery were identified (normal/mild [42%], moderate [49%], and severe [9%] anemia). Postoperative bleeding (2.1% vs. 2.2% vs. 2.2%) and 30-day outcomes including swelling (0.4% vs. 0.5% vs. 0.7%) and wound infection (0.4% vs. 0.3% vs. 0.1%) were similar in mild/normal, moderate, and severe anemia groups, respectively (All P > 0.05). However, 30-day mortality was significantly higher in patients with severe anemia compared with normal/mild and moderate anemia (2.1% vs. 1.1% and 1.1%, P < 0.001). After adjusting for potential confounders, severe anemia was associated with 90% higher risk of 30-day mortality (odds ratio [95% confidence interval]: 1.90 [1.20-3.00], P = 0.006) and 17% increase in PP loss at 1 year (adjusted hazard ratio [95% confidence interval]: 1.17 [1.02-1.35], P = 0.01) compared with the normal/mild anemia group. However, no significant difference was seen between normal/mild and moderate anemia.

CONCLUSIONS

In this large study of patients undergoing HD access placement, severe anemia was associated with 90% increased risk of 30-day mortality and 17% increased risk of loss of PP compared with those with normal/mild anemia. Management of severe anemia before surgery might be indicated to reduce operative mortality and improve the durability of HD access.

Vascular access care and treatment practices associated with outcomes of arteriovenous fistula: international comparisons from the Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Vascular access (VA) guidelines recommend the native arteriovenous fistula (AVF) as VA of first choice for chronic hemodialysis patients. AVF management is important in hemodialysis patient care. AVF survival is associated with various physical factors, but the effects of dialysis treatment factors upon AVF survival are still not clear.

METHODS

Study patients were treated at 498 dialysis facilities participating in the Dialysis Outcomes and Practice Patterns Study (DOPPS) 2 or 3 (2002-2007). Analyses included 1,183 incident hemodialysis patients (on dialysis ≤7 days and using an AVF at study entry) and 949 prevalent patients (on dialysis >7 days at DOPPS entry and using a new AVF created during study observation). AVF survival was modeled from the study entry date for incident patients and date of first AVF use for prevalent patients. Predictors of primary and final AVF survival were compared across Japan, North America and Europe/Australia/New Zealand (EUR/ANZ) with adjustments for patient characteristics.

RESULTS

No meaningful relationship was seen between AVF survival and various physician and staff practices. However, patients with prior catheter use displayed higher rates of primary and final AVF failure. Final AVF failure rates were higher in facilities with higher median blood flow rates (BFR). They were also greater in North America and EUR/ANZ than in Japan, but this difference was substantially attenuated after accounting for regional differences in facility median BFR.

CONCLUSION

AVF longevity differed according to the DOPPS region, and was related to prior patient catheter use and facility BFR practice. Further longitudinal studies may help demonstrate meaningful associations between VA-handling skill and patency.

Correlation of Mortality and Location of Arteriovenous Fistula in Hemodialysis Patients

Purpose

Since the type of vascular access is very important and a significant risk factor for mortality in patients on hemodialysis, the aim of our study was to determine the impact of AVF positioning on the mortality of our patients.

Methods

The survey was organized as a prospective, clinical and non-randomized study of 538 surgical interventions on 323 patients, which indicates that a large number of patients had more than one fistula. Among these patients, 120 subjects (81 (67.5%) men and 39 (32.5%) women) died during the study period. We analyzed the demographic structure, the site location and type of anastomosis for the arteriovenous fistula, artery and vein lumen and presence of instillation catheters, as well as measuring flow through the fistula and arterial blood pressure. Biochemical parameters thought to have a significant impact on survival were obtained from routine monthly analyses.

Results

In patients in whom infection was the cause of death, termino-terminal anastomosis was more frequently present (p=0.035). Variables that were statistically significant predictors of death were elderly individuals (Beta 0.033, p<0.001); patients whose diastolic blood pressure was low (Beta –0.028, p<0.001); and the position of the arteriovenous fistula (distal Beta –0.737, p=0.001; proximal Beta –0.581, p=0.008). Patients with a cubital fistula (p=0.001) had a significantly shorter Kaplan-Meier survival curve.

Conclusions

End-to-end artery and vein connection was a significantly more common form of anastomosis in patients who died as a result of infection. Important parameters of mortality in our study were the position of the arteriovenous fistula, age, and the diastolic component of arterial blood pressure.

[Problem of creation of arteriovenous fistulae for hemodialysis in older patients]

INTRODUCTION

A significant problem in elderly on hemodialysis is vascular access creation. The aim of the study was to determine the factors of functionality of arteriovenous fistulas in elderly people.

MATERIAL AND METHODS

Target groups in the four-year study were patients over 65 years of life. The authors analyzed the demographic structure, the etiology of kidney weakness, the type of anastomosis, arteriovenous fistula location, use of catheters from hemodialysis, blood pressure and size of the lumen of blood vessels used for anastomosis. Routine hematological and biochemical parameters were determined in all subjects. The study included 120 patients, 42 (35%) women and 78 (65%) men.

RESULTS

Functional arteriovenous fistulae were found in 62 (51.70%) patients, aged 72.5 +/- 4.23 years and nonfunctional ones in 58 (48.3%) respondents aged 72 +/- 5.09 years. A significant difference between the studied groups was reached in relation to the type of anastomosis (p = 0.005) and sites of the located fistulas (p = 0.03). Hypertensive nephropathy occurs statistically significantly more frequently in patients with functional fistula (p = 0.03). Sedimentation (p = 0.01), hemoglobin (p = 0.04), platelets (p = 0.003), total cholesterol (p = 0.04) and low density lipoproteins (p = 0.03) had statistically higher values in patients with nonfunctional fistulae.

CONCLUSION

Atherosclerosis and increased coagulation in the old people on hemodialysis represent an important cause of complications of arteriovenous fistulae.

Factors that condition the response to erythropoietin in patients on hemodialysis and their relation to mortality

The response to erythropoietin-stimulating agents (ESA) can vary among different patients and according to the different circumstances over time within a given individual. The aim of this study was to analyze the factors that can modify the response to epoetin in patients on hemodialysis (HD) and its influence on early mortality. Prospective and observational study including 1710 patients from 119 HD units in Spain with a follow-up of 12 months. To evaluate the dose-response effect of EPO therapy, we used the erythropoietin resistance index (ERI), calculated as the weekly weight-adjusted dose of EPO divided by the hemoglobin level. Patients were stratified in three groups according to ERI: group A, ERI <5; group B, ERI=5-15; group C, ERI>15 U/kg/week/g per 100 ml. Mean ERI for the entire group was 10.2+/-7.3 U/kg/week/g per 100 ml. ERI was directly related with incident comorbidity (Charlson Index), age, female gender and low body mass index with no relationship with etiology of chronic kidney disease. Patients with antecedents of heart failure, acute infection or malignant neoplasm had significantly higher ERI than those without. Transferrin saturation index, but not serum ferritin, was inversely related with ERI. Serum levels of albumin and cholesterol were related with lower ERI, but no relation was found with normalized protein catabolic rate. Patients with a permanent catheter for HD had significant higher values of ERI than those with native fistula (P=0.012). One year survival in all three groups of patients according to ERI was 0.916 in group A, 0.877 in group B and 0.788 in group C (log-rank=20.7, P<0.001). The resistance to ESA is directly related with incident comorbidity in patients on hemodialysis and it can be interpreted as a useful marker of early mortality.