Role of Vascular Access as a Risk Factor for Infections in Hemodialysis

Predictors of Mortality within 24 Months of Initial Arteriovenous Access Creation

INTRODUCTION

End Stage Renal Disease is increasingly common, with approximately 785,880 patients currently dialysis dependent in the United States. 86% of these patients utilize hemodialysis. Arteriovenous (AV) access with either a fistula or graft is preferred over a catheter due to lowered complication risk. The purpose of this paper is to identify mid- term predictors of mortality to guide the type of AV access in patients with suboptimal cephalic veins.

METHODS

This is a retrospective review of patient characteristics at the time of initial AV access placement. All patients receiving first time AV access were reviewed. Mortality data was found via electronic medical records review, social security death index review, and internet search. Patients in whom mortality data could not be found were excluded from the final analysis. Univariate analysis using Chi-Squared testing and Student T-Test was performed. Binary logistic regression analysis was also performed for multivariate investigation.

RESULTS

A total of 176 patients underwent first time AV access during the study period. Two year mortality data was available for 149 of these patients. Mortality occurred within 2 years for 27% of patients. Advanced age (70 vs. 61, P < 0.01), arrhythmia (48% vs. 24%, P < 0.01), abnormal EKG (36% vs.14%, P < 0.01), CHF (47% vs. 24%, P < 0.01), white, non-Hispanic race (51% vs. 22%, P < 0.01) and history of smoking (48% vs. 15%, P < 0.01) were statistically significant univariate predictors of 2-year mortality. Advanced age, white race and smoking were multivariate predictors with smoking having the largest impact (multivariate adjusted OR 11.8, P < 0.001).

CONCLUSIONS

History of tobacco smoking has a profoundly negative effect on two year survival in patients undergoing initial AV access. Absence of smoking history provides significant 2-year mortality protection and thorough attempt at autologous AVF creation should be made in these patients. Cardiac disease and advanced age continue to be lead predictors of mortality in ESRD patients.

Analysis of Different Vascular Accesses on Dialysis Quality and Infection Risk Factors of Hemodialysis Patients

Objective

To explore the influence of different vascular accesses on dialysis quality and infection risk factors of hemodialysis patients.

Methods

A total of 162 patients with end-stage renal disease admitted to our hospital from February 2018 to July 2020 were divided into two groups: cuff tunnel conduit (CTC) group and native arteriovenous fistula (AVF) group. Peripheral blood was collected before and 6 months after dialysis. The incidence of vascular recirculation was measured, and the risk factors of infection were analyzed.

Results

The levels of HB, Alb, CRP, BUN, Scr, and TP after dialysis in the two groups were lower than those before dialysis (P < 0.05). The Kt/V of patients in both groups did not exceed 1.2, and the URR value exceeded 60%. The results of independent-samples T test analysis documented that the Kt/V level of patients in the AVF group was higher than that of those in the CTC group after dialysis (P < 0.05). The results of the urea method revealed that 22 of 68 patients (32.35%) in the CVC group and 21 of 94 (22.34%) in the AVF group had vascular pathway recirculation. The χ² test showed that there was no remarkable difference in the incidence of vascular pathway recirculation between both groups (P > 0.05). However, the results of the nonurea method revealed that the incidence of vascular pathway recirculation in the AVF group was lower than that in the CVC group (P < 0.05). Multivariate logistic regression was used to further analyze the factors with statistical significance in the single factor results. It showed that age >60 years, dialysis duration >1 year, dialysis times, diabetes, hypertension, and CTC were all independent risk factors causing vascular access infection.

Conclusion

If all conditions permit, AVF hemodialysis is a better choice for patients with end-stage renal disease. For the elderly, long-term hemodialysis, and those with diabetes and hypertension, it is necessary to make detailed plans, strengthen the operation proficiency of CTC, and reduce the incidence of infection.

FEASIBILITY OF SMART HEMODIALYSIS PATIENT CARE USING SENSORS EMBEDDED IN PERSONALIZED 3D PRINTING CAST

The ever-increasing incidence of end-stage renal disease (ESRD) has already become a major burden to health budgets and a threat to public health nationwide in Taiwan. According to the United States Renal Data System Annual Data Report in 2015, the prevalence and incidence of ESRD in Taiwan are the highest in the world. Moreover, for the population of 82 thousand ESRD patients receiving hemodialysis treatments, the total cost is up to NT$34.2 billion annually out of the National Health Insurance (NHI) program budget. This project is to design a wearable medical device which can measure and monitor the fluid dynamics of the dialysis access using sensor of phonoangiography (PAG) for exploring vascular pitch pattern and sensor of Photoplethysmography (PPG) for estimating the flow volume as a double checking of the AV access condition. We use arteriovenous access (AVA) stenosis detector based on phonoangiography technique and autoregressive model to detect access stenosis and simultaneously estimate the status of AVA life cycle by tracking and obtaining changes in frequency spectra domain. It helps hemodialysis patients to be aware earlier of the dysfunction of AVA and reminds them to make a return visit. The purpose of the complement deployment of vital sign sensors is to improve the prognosis and optimize overall health by providing analysis of physiological signals, including water content index, pulse oximetry, and blood pressure at the same time. With these sensors, the concept of holistic hemodialysis patient care (HHPC) might be proved.

Microsurgical approach for hemodialysis access: A pilot study of Brescia-Cimino fistulas constructed under microscopic guidance

The distal forearm is the preferred site for hemodialysis access. However, forearm vessels have small diameter, which may lead to complications of arteriovenous fistulas constructed at this site. Indeed, the mean patency rate of such fistulas has been reported at 65.2% (range, 56-79%) at 1 year postoperatively. In this study, we aimed to evaluate the patency rate of Brescia-Cimino arteriovenous fistulas constructed under microscopic guidance. We retrospectively evaluated the records of patients with chronic renal failure who received a Brescia-Cimino arteriovenous fistula between 2014 and 2015 for hemodialysis access. Preoperative venography and Doppler mapping were used to evaluate vein diameter at the wrist. Veins with a diameter of >2 mm were chosen. End-to-side microanastomosis was performed using Nylon #9-0 suture under microscopic guidance. Postoperatively, monthly follow-up (first with venography; with Doppler ultrasound thereafter) was conducted to detect vessel obstruction and evaluate blood flow. Six of the seven patients included in this study received hemodialysis without signs of obstruction or complications. On Kaplan-Meier survival analysis, the mean patency rate at 2 years postoperatively was 85.7%. One patient (female, 60 years) had vessel obstruction and underwent percutaneous transluminal angioplasty 3 times after receiving the arteriovenous fistula. The median follow-up duration was 41 months (range, 25-47 months). Our experience indicates that, for relatively healthy vessels with a diameter of >2 mm, Brescia-Cimino arteriovenous fistulas at the wrist can be safely constructed using microsurgical suturing under microscopic guidance, without complications such as ischemic hand syndrome or infection.

Hemodialysis-Associated Infections

Hemodialysis patients are at increased risk of infections, which are common adverse events among this patient population. We review factors contributing to infections among hemodialysis patients and epidemiology of common infections and outbreaks, including bloodstream infections, vascular access infections, and infections caused by bloodborne pathogens. Recommendations for prevention are discussed with emphasis on essential infection control practices for hemodialysis settings.

Rate of bacteremia in the hemodialysis patient presenting to the emergency department with fever: a retrospective chart review

BACKGROUND

Infectious disease is the second most common cause of death in patients receiving hemodialysis (HD). When presenting to the emergency department (ED) with fever, it remains a diagnostic challenge to distinguish patients with potentially life-threatening bacterial infections from those with less significant causes of fever. The primary goal of this study was to determine the rate of bacteremia in HD patients presenting to the ED with fever. The secondary goal of this study was to identify any independent risk factors associated with bacteremia in the febrile HD patient.

METHODS

This is a retrospective medical record review of all HD patients who presented to the ED with either subjective fever as primary complaint or with a documented triage temperature of 38 °C or higher during the 3-year period between September 1, 2014, and September 1, 2017. Patient visits were included in the study if blood cultures were ordered in the ED. Data related to demographic information, clinical parameters, diagnostic test results in the ER, final diagnosis, and results of microbiology cultures were collected from each patient encounter. Univariate analysis was performed to identify risk factors associated with bacteremia.

RESULTS

We identified 353 patient visits from 138 unique patients that met inclusion criteria. Fifty-eight percent of these were women, and the average age was 54.6 years. The rate of bacteremia was 31.7%, and the main microorganisms isolated in blood culture were non-MRSA Staphylococcus aureus (40.7%), MRSA (13.3%), Pseudomonas aeruginosa (11.5%), and Enterobacter spp. (11.5%). Independent prognostic factors associated with bacteremia were use of dialysis catheter, prior history of bacteremia, and > 5% neutrophilic band cells (OR 6.55 [95% CI 3.96-10.8; p < 0.0001]; OR 8.87 [95% CI 5.32-14.8; p < 0.0001]; OR 3.32 [95% CI 1.90-5.80; p < 0.0001] respectively).

CONCLUSION

HD patients presenting to the ED with fever have high rates of bacteremia, with a significantly higher rate in patients using dialysis catheters or those with a history of bacteremia. Other clinical data available in the ED is minimally useful in predicting bacteremia.

Early use of autogenous arteriovenous fistula in patients with urgent hemodialysis

PURPOSE

This study was designed to evaluate the long-term patency rate and complications associated with early use of the autogenous forearm arteriovenous fistula (AFAVF) in patients needing urgent hemodialysis.

METHODS

The clinical data of all patients undergoing AFAVFs for hemodialysis access between June 1996 and June 2016 were retrospectively evaluated. The primary and secondary patencies were estimated using the life table method.

RESULTS

A total of 104 AFAVFs were created for 102 patients. All patients had entered hemodialysis when fistulas were constructed. The mean time to the first cannulation of the AFAVF was 17.33 ± 4.60 (5-27 days). Four AFAVFs (3.8%) became occluded within 30 days of creation of the access, and five AFAVFs (4.8%) had hematomas after cannulation. There were no cases of infection of the wound or steal syndrome or prolonged arm edema. The primary patency rate was 77.81% at 1 year, 73.05% at 2 years, 64.64% at 3 years, 60.75% at 5 years and 47.48% at 10 years. The secondary patency rate was 96.78% at 1 year, 95.18% at 5 years and 85.81% at 10 years.

CONCLUSIONS

In this study, the patency rates following the early use of the AFAVFs were not inferior to the previously reported patency rates in the literature. For patients entering hemodialysis with an inserted central catheter, the early use of the AFAVFs decreases the complications associated with catheters.

A Taurolidine-Citrate-Heparin Lock Solution Effectively Eradicates Pathogens From the Catheter Biofilm in Hemodialysis Patients

Catheter-related bacteremia (CRB) is a typical complication of hemodialysis catheter use. Catheter lumen colonization by pathogens is regarded as a direct cause of CRB. Once settled, the catheter biofilm increases the risk of developing infection, thus necessitating insertion replacement and antibiotic treatment. The study assessed the self-sufficient efficacy of taurolidine-citrate-heparin lock solution in eradicating catheter biofilm bacteria and keeping it sterile in patients on hemodialysis. Twenty-nine chronic patients on hemodialysis with tunneled and nontunneled catheters locked with a heparin filling (the mean time of heparin lock use -30.1 ± 2.0 days) and subsequently converted to a taurolidine-citrate-heparin filling were included. Peripheral vein and catheter lumen blood cultures were obtained before the filling change and after taurolidine-citrate-heparin lock use (mean time 33.8 ± 7.6 days). Twenty-four participants with tunneled and nontunneled catheters locked with taurolidine-citrate-heparin filling served as the control group. During the heparin-locking period, CRB was diagnosed in 3 cases (only nontunneled catheters). The catheter blood cultures findings were positive in 23 patients (10 temporary and 13 permanent catheters), whereas both the catheter and peripheral vein blood cultures were sterile in 3 of 29 subjects (only permanent catheters). Irrespective of catheter type (tunneled or nontunneled), repeated culture revealed no pathogens in any of the 23 patients with initial positive catheter blood culture, after the use of taurolidine-citrate-heparin filling. No positive blood culture was noted in the control group. The taurolidine-citrate-heparin lock solution effectively eradicated pathogens from nontunneled and tunneled catheter biofilms and helped to maintain catheter lumen sterility.

Adipose phenotype predicts early human autogenous arteriovenous hemodialysis remodeling

OBJECTIVE

Substantial proportions of autogenous arteriovenous fistulas (AVFs) for hemodialysis access fail to mature for unclear reasons. AVFs develop in a large mass of surrounding adipose tissue that is increasingly recognized as an active participant in the vascular response to injury via paracrine and endocrine mechanisms. We thus hypothesized that baseline phenotypic characteristics of the adipose tissue juxtaposed to the developing AVF associate with subsequent inward or outward vein wall remodeling.

METHODS

Clinical data and subcutaneous adipose tissue were collected from 22 consented patients undergoing AVF creation. Tissue was assayed (protein levels) for interleukin (IL)-6, IL-8, leptin, tumor necrosis factor-α, monocyte chemoattractant protein-1 (MCP-1), resistin, and adiponectin. Vein dimensions were acquired by duplex ultrasound imaging, preoperatively and at 4 to 6 weeks postoperatively, 1 cm cephalad to the arteriovenous anastomosis, which is the most common location of AVF stenosis).

RESULTS

The vein at the assayed location outwardly remodeled 55.7% on average (median before, 3.7 mm; median after, 4.7 mm; P = .005). The preoperative vein diameter failed to correlate with postoperative size at the point of assay (R = 0.31; P = .155) unless two outliers were excluded (R = 0.64; P = .002). After removal of the same outliers, the correlation coefficient between venous diameter change (preoperative vs postoperative) and IL-8, tumor necrosis factor-α, MCP-1, resistin, and adiponectin was -0.49, -0.79, -0.66, -0.64, and -0.69, respectively (P < .05). Postoperative AVF flow volume correlated with MCP-1 (R = -0.53; P < .05) and adiponectin (R = -0.47; P < .05).

CONCLUSIONS

These data reveal a novel relationship between local adipose phenotype and the eventual venous wall response to hemodynamic perturbation in humans. The predictive value of these mediators generally equaled or exceeded that of preoperative vein size. Beyond providing mechanistic insights into vascular wall adaptations due to flow perturbations, this discovery suggests that strategies focused on altering adipose tissue biology may improve AVF maturation.

Preserving arteriovenous fistula outcomes during surgical training

PURPOSE

Arteriovenous fistulae (AVFs) are the preferred option for vascular access, as they are associated with lower mortality in hemodialysis patients than in those patients with arteriovenous grafts (AVGs) or central venous catheters (CVCs). We sought to assess whether vascular access outcomes for surgical trainees are comparable to fully trained surgeons.

METHODS

A prospectively collected database of patients was created and information recorded regarding patient demographics, past medical history, preoperative investigations, grade of operating surgeon, type of AVF formed, primary AVF function, cumulative AVF survival and functional patency.

RESULTS

One hundred and sixty-two patients were identified as having had vascular access procedures during the 6 month study period and 143 were included in the final analysis. Secondary AVF patency was established in 123 (86%) of these AVFs and 89 (62.2%) were used for dialysis. There was no significant difference in survival of AVFs according to training status of surgeon (log rank x2 0.506 p=0.477) or type of AVF (log rank x2 0.341 p=0.559). Patency rates of successful AVFs at 1 and 2 years were 60.9% and 47.9%, respectively.

CONCLUSION

We have demonstrated in this prospective study that there are no significant differences in outcomes of primary AVFs formed by fully trained surgeons versus surgical trainees. Creation of a primary AVF represents an excellent training platform for intermediate stage surgeons across general and vascular surgical specialties.

An approach to addressing selection bias in survival analysis

This work proposes a frailty model that accounts for non-random treatment assignment in survival analysis. Using Monte Carlo simulation, we found that estimated treatment parameters from our proposed endogenous selection survival model (esSurv) closely parallel the consistent two-stage residual inclusion (2SRI) results, while offering computational and interpretive advantages. The esSurv method greatly enhances computational speed relative to 2SRI by eliminating the need for bootstrapped standard errors and generally results in smaller standard errors than those estimated by 2SRI. In addition, esSurv explicitly estimates the correlation of unobservable factors contributing to both treatment assignment and the outcome of interest, providing an interpretive advantage over the residual parameter estimate in the 2SRI method. Comparisons with commonly used propensity score methods and with a model that does not account for non-random treatment assignment show clear bias in these methods, which is not mitigated by increased sample size. We illustrate using actual dialysis patient data comparing mortality of patients with mature arteriovenous grafts for venous access to mortality of patients with grafts placed but not yet ready for use at the initiation of dialysis. We find strong evidence of endogeneity (with estimate of correlation in unobserved factors ρ^=0.55) and estimate a mature-graft hazard ratio of 0.197 in our proposed method, with a similar 0.173 hazard ratio using 2SRI. The 0.630 hazard ratio from a frailty model without a correction for the non-random nature of treatment assignment illustrates the importance of accounting for endogeneity.

Agreement of reported vascular access on the medical evidence report and on medicare claims at hemodialysis initiation

BACKGROUND

The choice of vascular access type is an important aspect of care for incident hemodialysis patients. However, data from the Centers for Medicare & Medicaid Services (CMS) Medical Evidence Report (form CMS-2728) identifying the first access for incident patients have not previously been validated. Medicare began requiring that vascular access type be reported on claims in July 2010. We aimed to determine the agreement between the reported vascular access at initiation from form CMS-2728 and from Medicare claims.

METHODS

This retrospective study used a cohort of 9777 patients who initiated dialysis in the latter half of 2010 and were eligible for Medicare at the start of renal replacement therapy to compare the vascular access type reported on form CMS-2728 with the type reported on Medicare outpatient dialysis claims for the same patients. For each patient, the reported access from each data source was compiled; the percent agreement represented the percent of patients for whom the access was the same. Multivariate logistic analysis was performed to identify characteristics associated with the agreement of reported access.

RESULTS

The two data sources agreed for 94% of patients, with a Kappa statistic of 0.83, indicating an excellent level of agreement. Further, we found no evidence to suggest that agreement was associated with the patient characteristics of age, sex, race, or primary cause of renal failure.

CONCLUSION

These results suggest that vascular access data as reported on form CMS-2728 are valid and reliable for use in research studies.

Incidence of nosocomial hemodialysis-associated bloodstream infections at a county teaching hospital

BACKGROUND

Infections are an important cause of morbidity and mortality in patients undergoing hemodialysis. Limited information is to be found regarding nosocomial hemodialysis-associated bloodstream infections (HABSI).

METHODS

We sought to determine the rate of nosocomial HABSI and its associated risk factors at Riverside County Regional Medical Center. Inpatients who received hemodialysis during 2011 and 2012 were included, and outcomes were recorded along with risk factors. Data was analyzed with SPSS Inc software.

RESULTS

A total of 619 patients was included. Fourteen HABSI were detected, with a rate of 3.33/1,000 hemodialysis sessions and 1.03/1,000 patient-days. An association was detected between HABSI and vascular access type (highest risk with nontunneled catheters), length of hospital stay, number of hemodialysis sessions, and hemoglobin A1c level. A correlation was also noted between HABSI because of MRSA and colonization of nares with MRSA. A predominance of staphylococci infections was detected.

CONCLUSION

The rate of HABSI observed at Riverside County Regional Medical Center was lower than similar studies (2.5 per 1,000 patient-days and 3.95 per 1,000 hemodialysis sessions). The most important risk factors were determined to be nontunneled catheters, hemoglobin A1c greater than 7%, and nares colonization for HABSI because of MRSA. Infection prevention efforts in the inpatient hemodialysis population should focus on control of hyperglycemia and decolonization of nares from MRSA.

Health status as a potential mediator of the association between hemodialysis vascular access and mortality

BACKGROUND

It is unknown whether the selection of healthier patients for arteriovenous fistula (AVF) placement explains higher observed catheter-associated mortality among elderly hemodialysis patients.

METHODS

From the United States Renal Data System 2005-2007, we used proportional hazard models to examine 117 277 incident hemodialysis patients aged 67-90 years for the association of initial vascular access type and 5-year mortality after accounting for health status. Health status was defined as functional status at dialysis initiation and number of hospital days within 2 years prior to dialysis initiation.

RESULTS

Patients with catheter alone had more limited functional status (25.5 versus 10.8% of those with AVF) and 3-fold more prior hospital days than those with AVF (mean 18.0 versus 5.4). In the unadjusted model, the likelihood of death was higher for arteriovenous grafts (AVG) {Hazard ratio (HR) 1.20 [95% CI (1.16-1.25)], catheter plus AVF [HR 1.34 (1.31-1.38)], catheter plus AVG [HR 1.46 (1.40-1.52)] and catheter only [HR 1.95 (1.90-1.99)]}, compared with AVF (P < 0.001). The association attenuated -23.7% (95% CI -22.0, -25.5) overall (AVF versus all other access types) after adjusting for the usual covariates (including sociodemographics, comorbidities and pre-dialysis nephrology care) {AVG [HR 1.21 (1.17-1.26)], catheter plus AVF [HR 1.27 (1.24-1.30)], catheter plus AVG [HR 1.38 (1.32-1.43)] and catheter only [HR 1.69 (1.66-1.73)], P < 0.001}. Additional adjustment for health status further attenuated the association by another -19.7% (-18.2, -21.3) overall but remained statistically significant <AVG [HR 1.18 (1.13-1.22)], catheter plus AVF [HR 1.20 (1.17-1.23)], catheter plus AVG {HR 1.38 [1.26 (1.21-1.31)]} and catheter only [HR 1.54 (1.50-1.58)], P < 0.001>.

CONCLUSIONS

The observed attenuation in mortality differences previously attributed to access type alone suggests the existence of selection bias. Nevertheless, the persistence of an apparent survival advantage after adjustment for health status suggests that AVF should still be the access of choice for elderly individuals beginning hemodialysis until more definitive data eliminating selection bias become available.

Disparities in arteriovenous fistula placement in older hemodialysis patients

The benefits of an arteriovenous fistula (AVF) as the preferred vascular access for hemodialysis have been clearly demonstrated. However, only about 20% of patients in the United States initiate hemodialysis with an AVF. In this study, we assessed whether disparities exist in the type of first hemodialysis access placed prior to dialysis start (rather than that used at dialysis initiation), to detect whether certain disadvantaged groups might have lower likelihood of AVF placement. Study cohort of 118,767 incident hemodialysis patients ≥67 years of age (1/2005-12/2008) derived from the United States Renal Data System was linked with Medicare claims data to identify the type of initial access placed predialysis. We used logistic regression model with outcome being the initial predialysis placement of an AVF as opposed to an arteriovenous graft or a central venous catheter. Increasing age, female sex, black race, lower body mass index, urban location, certain comorbidities, and shorter pre-end-stage renal disease nephrology care are all associated with a significantly lower likelihood of AVF placement as initial access predialysis. Our study suggests the presence of significant disparities in the placement of an AVF as initial hemodialysis vascular access. We suggest that additional attention should be paid to these patient groups to improve disparities by patient education, earlier referral, and close follow-up.

Hemodialysis access usage patterns in the incident dialysis year and associated catheter-related complications

BACKGROUND

Hemodialysis (HD) access is considered a critical and actionable determinant of morbidity, with a growing literature suggesting that initial HD access type is an important marker of long-term outcomes. Accordingly, we examined HD access during the incident dialysis period, focusing on infection risk and successful fistula creation during the first dialysis year.

STUDY DESIGN

Longitudinal cohort.

SETTING & PARTICIPANTS

All US adults admitted to Fresenius Medical Care North America facilities within 15 days of first maintenance dialysis session between January 1 and December 31, 2007.

PREDICTOR

Vascular access type at HD therapy initiation.

OUTCOMES

Vascular access type at 90 days and at the end of the first year on HD therapy, bloodstream infection within the first year by access type, and catheter complication rate.

RESULTS

Of 25,003 incident dialysis patients studied, 19,622 (78.5%) initiated dialysis with a catheter; 4,151 (16.6%), with a fistula; and 1,230 (4.9%), with a graft. At 90 days, 14,105 (69.7%) had a catheter, 4,432 (21.9%) had a fistula, and 1,705 (8.4%) had a graft. Functioning fistulas and grafts at dialysis therapy initiation had first-year failure rates of 10% and 15%, respectively. Grafts were seldom replaced by fistulas (3%), whereas 7,064 (47.6%) of all patients who initiated with a catheter alone still had only a catheter at 1 year. Overall, 3,327 (13.3%) patients had at least one positive blood culture during follow-up, with the risk being similar between the fistula and graft groups, but approximately 3-fold higher in patients with a catheter (P<0.001 for either comparison). Nearly 1 in 3 catheters (32.5%) will require tissue plasminogen activator use by a median of 41 days, with 59% requiring more than one tissue plasminogen activator administration.

LIMITATIONS

Potential underestimation of bacteremia because follow-up blood culture results did not include samples sent to local laboratories.

CONCLUSIONS

In a large and representative population of incident US dialysis patients, catheter use remains very high during the first year of HD care and is associated with high mechanical complication and bloodstream infection rates.

Timing of arteriovenous fistula placement and Medicare costs during dialysis initiation

BACKGROUND/AIMS

Arteriovenous fistulas (AVFs) appear to be clinically superior to catheters as vascular access for maintenance hemodialysis, but higher insertion costs and high disease burden and mortality obscure the issue of whether AVF placement before hemodialysis initiation represents a net cost savings. We aimed to investigate Medicare costs for patients beginning maintenance hemodialysis, as related to timing of AVF placement.

METHODS

Data were from Medicare claims for incident hemodialysis patients aged ≥67 years in 2006. The study period extended from 2 years before to 1 year after dialysis initiation. Patients identified as having AVFs were categorized by timing of placement (mature AVF at dialysis initiation, maturing AVF at initiation, postinitiation AVF placement). Because timing may be influenced by factors that also influence overall costs, the model accounted for this nonrandom treatment assignment. An ordered probit extension of the classic Heckman correction was employed after identifying an appropriate instrumental variable. A cohort with Medicare coverage before and after dialysis initiation was identified, and Medicare claims were used to identify comorbid conditions and treatment costs.

RESULTS

Principal findings are that earlier AVF placement leads to lower costs, with the potential for about USD 500 million in savings. Additionally, the effect of nonrandom treatment assignment is real and significant. In our data, the impact of AVF placement timing was understated when treatment selection was ignored.

CONCLUSIONS

For appropriate AVF candidates, having a mature AVF in place at the time of dialysis initiation appears to confer cost savings.

Superior patency of upper arm arteriovenous fistulae in high risk patients

BACKGROUND

Despite an increased propensity to primary failure in forearm arteriovenous fistulae compared with upper arm fistulae, forearm fistulae remain the preferred primary access type for chronic hemodialysis patients. In a high risk patient population with multiple medical comorbidities associated with requirement for intravenous access we compared the rates of access failure in forearm and upper arm fistulae.

MATERIALS AND METHODS

The records of all patients having primary native arteriovenous fistulae placed between 2004 and 2009 at the VA Connecticut Healthcare system were reviewed (n = 118). Primary and secondary patency of upper arm and forearm fistulae were evaluated using Kaplan-Meier survival analysis. The effects of medical comorbidities on access patency were analyzed with Cox regression.

RESULTS

The median time to primary failure of the vascular access was 0.288 y in the forearm group compared with 0.940 y in the upper arm group (P = 0.028). Secondary patency was 52% at 4.9 y in upper arm fistulae compared with 52% at 1.1 y in the forearm group (P = 0.036). There was no significant effect of patient comorbidities on fistula failure; however, there was a trend toward upper arm surgical site as a protective factor for primary fistula patency (hazard ratio = 0.573, P = 0.076).

CONCLUSIONS

In veterans needing hemodialysis, a high risk population with extensive comorbid factors often requiring intravascular access, upper arm fistulae are not only a viable option for primary vascular access, but are likely to be a superior option to classic forearm fistulae.

Choice of vascular access among incident hemodialysis patients: a decision and cost-utility analysis

BACKGROUND AND OBJECTIVES

Arteriovenous fistulas (AVFs) are widely accepted as the preferred hemodialysis vascular access type. However, supporting data have failed to consider morbidity and mortality incurred during failed creation attempts and may therefore overstate potential advantages. This study compares survival, quality-adjusted survival, and costs among incident hemodialysis patients after attempted placement of AVFs or arteriovenous grafts (AVGs).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Analogous Markov models were created, one each for AVF and AVG. Patients entered consideration at the time of first access creation, contemporaneous with dialysis initiation. Subsequent outcomes were determined probabilistically; transition probabilities, utilities, and costs were gathered from published sources. To ensure comparability between AVFs and AVGs, the timing and likelihood of access maturation were measured in a contemporary cohort of incident hemodialysis patients.

RESULTS

Mean (SD) overall survival was 39.2 (0.8) and 36.7 (1.0) months for AVFs and AVGs, respectively: difference (95% confidence interval [CI]) 2.6 (1.8, 3.3) months. Quality-adjusted survival was 36.1 (0.8) and 32.5 (0.9) quality-adjusted life months (QALMs) for AVFs and AVGs, respectively: difference (95% CI) 3.6 (2.8, 4.3) QALMs. The incremental cost-effectiveness ratio (95% CI) for AVFs relative to AVGs was $446 (-6023, 6994) per quality-adjusted life year saved.

CONCLUSIONS

AVFs are associated with greater overall and quality-adjusted survival than AVGs. Observed differences were much less pronounced than might be expected from existing literature, suggesting that prospective identification of patients at high risk for AVF maturational failure might enable improvements in health outcomes via individualization of access planning.

Facility hemodialysis vascular access use and mortality in countries participating in DOPPS: an instrumental variable analysis

BACKGROUND

Previously, the Dialysis Outcomes and Practice Patterns Study (DOPPS) has shown large international variations in vascular access practice. Greater mortality risks have been seen for hemodialysis (HD) patients dialyzing with a catheter or graft versus a native arteriovenous fistula (AVF). To further understand the relationship between vascular access practice and outcomes, we have applied practice-based analyses (using an instrumental variable approach) to decrease the treatment-by-indication bias of prior patient-level analyses.

STUDY DESIGN

A prospective observational study of HD practices.

SETTING & PARTICIPANTS

Data collected from 1996 to 2004 from 28,196 HD patients from more than 300 dialysis units participating in the DOPPS in 12 countries.

PREDICTOR OR FACTOR

Patient-level or case-mix-adjusted facility-level vascular access use. OUTCOMES/MEASUREMENTS: Mortality and hospitalization risks.

RESULTS

After adjusting for demographics, comorbid conditions, and laboratory values, greater mortality risk was seen for patients using a catheter (relative risk, 1.32; 95% confidence interval, 1.22 to 1.42; P < 0.001) or graft (relative risk, 1.15; 95% confidence interval, 1.06 to 1.25; P < 0.001) versus an AVF. Every 20% greater case-mix-adjusted catheter use within a facility was associated with 20% greater mortality risk (versus facility AVF use, P < 0.001); and every 20% greater facility graft use was associated with 9% greater mortality risk (P < 0.001). Greater facility catheter and graft use were both associated with greater all-cause and infection-related hospitalization. Catheter and graft use were greater in the United States than in Japan and many European countries. More than half the 36% to 43% greater case-mix-adjusted mortality risk for HD patients in the United States versus the 5 European countries from the DOPPS I and II was attributable to differences in vascular access practice, even after adjusting for other HD practices. Vascular access practice differences accounted for nearly 30% of the greater US mortality compared with Japan.

LIMITATIONS

Possible existence of unmeasured facility- and patient-level confounders that could impact the relationship of vascular access use with outcomes.

CONCLUSIONS

Facility-based analyses diminish treatment-by-indication bias and suggest that less catheter and graft use improves patient survival.

Vascular access infection among hemodialysis patients in Northern Jordan: incidence and risk factors

OBJECTIVES

Vascular access infection (VAI) causes significant mortality and morbidity in hemodialysis patients. The aim of this prospective, descriptive, exploratory survey of end-stage renal disease patients was to explore the incidence and risk factors of VAI.

METHODS

A total of 188 patients were included in the study from five different hospital/dialysis units in northern Jordan. All patients answered a questionnaire related to their vascular access (VA) and infection. Demographic information, etiology of renal failure, and infection history related to the access were also collected and analyzed.

RESULTS

Diabetes mellitus was the most common etiology of renal failure, followed by hypertension, urinary tract infection, and congenital malformation. The infection rate was variable according to the hospital and the type of VA; of 188 patients, 65 patients had a VAI during the year of study. Of these, 36 of 64 were because of catheters, 24 of 105 were because of arteriovenous fistulas (AVFs), and 5 of 19 were because of arteriovenous graft. Of the 65 with a VAI, 58 patients had a low level of education.

CONCLUSIONS

VAI was common in hemodialysis patients, and the risk varied substantially among different VA types and different dialysis units. The infection rate from catheters and AVFs was similar to that reported in many studies, but the infection rate in the arteriovenous graft group was lower than that for AVFs. These results can be improved by strictly following the National Kidney Foundation Disease Output Quality Initiative clinical practice guidelines for dialysis access.

Vascular access for hemodialysis: 2004 and beyond

PURPOSE OF REVIEW

Developments in vascular access are accruing rapidly. The last systematic Kidney Disease Outcomes Quality Initiative guidelines review took place in 2000. The purpose of this review is to update several major areas in which clear progress has been made. A major 'Fistula First Initiative' in the USA is an attempt to increase markedly the fraction of patients receiving an autologous arteriovenous fistula as opposed to a graft. Preoperative mapping to evaluate veins and artery may permit construction of arteriovenous fistula in up to 70% of all patients, thereby reducing access thrombosis, infection, and perhaps increasing survival of patients.

RECENT FINDINGS

Although a number of different synthetic materials have been tried, none seems to have any definite advantage over plain expanded polytetrafluoroethylene for constructing synthetic bridge grafts. Two developments may influence practice: use of composite self-sealing grafts that can be used within hours may eliminate the need for temporary catheters; and use of nitinol surgical clips may reduce endothelial trauma and improve patency. Large-bore catheters can deliver blood flows of over 400 ml/min initially, but they are prone to progressive occlusion. Optimal means of using a fibrinolytic to preserve flow must be evaluated. Surveillance techniques are undergoing rapid re-evaluation. Finally, a variety of antibiotic lock techniques are being evaluated for their ability to prevent catheter-related infections.

SUMMARY

Greater efforts must be made to establish pre-end-stage renal disease programs to educate and prepare patients for hemodialysis and improve arteriovenous fistula placement rates, and to encourage clinicians to re-examine their current clinical practices and dedicate themselves to improving vascular access outcomes.

Veterinary hemodialysis: advances in management and technology

Hemodialysis (HD) is a renal replacement therapy that can enable recovery of patients in acute kidney failure and prolong survival for patients with end-stage kidney failure. HD is also uniquely suited for management of refractory volume overload and removal of certain toxins from the bloodstream. Over the last decade, veterinary experience with HD has deepened and refined and its geographic availability has increased. As awareness of the usefulness and availability of dialytic therapy increases among veterinarians and pet owners and the number of veterinary dialysis facilities increases, dialytic management will become the standard of advanced care for animals with severe intractable uremia.