Vascular access outcomes in the elderly hemodialysis population: A USRDS study

Arteriovenous fistulae (AVF) are widely regarded as the preferred vascular access in hemodialysis (HD) patients due to their primary patency and patient survival benefits. Recent scholarship has suggested that the elderly population differs significantly from the general population in terms of inflammatory markers. What is more, recent studies have suggested that the elderly HD population is less likely to have an AVF placed as the initial vascular access compared to a younger cohort. The purpose of this study is to investigate the applicability of current vascular access guidelines to the elderly HD population. We hypothesized that the elderly HD population would derive less patency and survival benefit from AVF placement relative to arteriovenous graft (AVG) than the general population is known to derive. We performed a retrospective analysis using the US Renal Data System (USRDS) Wave II dataset to explore significant predictors of referral for intervention or access failure, and patient survival in the elderly US HD population using Cox regression corrected for race, gender, peripheral vascular disease, diabetes mellitus, and nutritional status. Of the 1471 HD patients with AVF or AVG, 764 patients were >65 years. Elderly diabetics had no significant mortality benefit from the use of AVF compared to AVG [odds ratio (OR) 1.34 (95% CI 0.92-1.95), p = 0.123]. Likewise, elderly nondiabetics had no significant mortality benefit from the use of AVF compared to AVG [OR 1.05 (95% CI 0.81-1.36), p = 0.735]. Elderly diabetics had no difference in odds for intervention referral for AVF compared to AVG [OR 1.49 (95% CI 0.76-2.9), p = 0.24]. Elderly nondiabetics had no difference in odds for intervention referral for AVF compared to AVG [OR 1.48 (95% CI 0.95-2.3), p = 0.08]. We conclude that the potential benefits derived from AVFs compared with AVGs and central venous catheters (CVC) may not apply universally. The recommendations of vascular access choice stipulated by national guidelines may need to be modified for elderly patients.     

Obesity as a predictor of vascular access outcomes: analysis of the USRDS DMMS Wave II study

Arteriovenous fistulae (AVF) are widely regarded as the preferred vascular access in hemodialysis patients due to their primary patency and patient survival benefits. While the obesity paradox has been associated with improved cardiovascular morbidity and all-cause mortality in dialysis patients, its long-term vascular access outcomes are less clear. Recent literature has suggested that obese patients may have increased early and late fistula failure. The purpose of this study was to explore the relationships between obesity and vascular access outcomes. We performed a retrospective cohort analysis using the USRDS DMMS Wave 2 data set. All incident dialysis patients as of January 1, 1996, over the age of 18, receiving only hemodialysis as mode of renal replacement therapy were eligible for inclusion. Among other variables, data collected for the DMMS Wave 2 included: type and location of vascular access, AVF maturity, vascular access revision, and failure. Logistic regression analyses were used to examine the relationships between obesity and vascular access outcomes, adjusting for important covariates. In all, 1486 hemodialysis patients were included. Using body mass index (BMI) <30 kg/m(2) as reference, obesity did not emerge as a factor in predicting vascular access revisions or failures. An increased risk of AVF failure to mature was found only in the highest BMI quartile (>or=35 kg/m(2)) (aOR 3.66 [95% CI 1.27-10.55], p = 0.017). Peripheral vascular disease was independently associated with an increased risk of AVF failure (aOR 2.78 [95% CI 1.01-7.63], p = 0.047) and arteriovenous graft (AVG) failure (aOR 1.65 [95% CI 1.03-2.64], p = 0.036). Obesity was not associated with increased AVF or AVG revision rates or failure and only associated with poorer AVF maturity at highest BMI quartile. We conclude that obesity should not preclude placement of AVF as vascular access of choice, except in the very obese where assessment should be individually based.     

Evaluation of Gore-Tex graft patency in hemodialysis access

Aim: The purpose of this retrospective study was to analyze the patency and complications of Gore-Tex grafts used in hemodialysis (HD) access. Methods: In the last 16 years, 1649 surgical procedures were performed on 655 patients to ensure and maintain permanent HD access. The study group consisted of 64 HD patients on whom 81 vascular synthetic PTFE Gore-tex grafts were performed. There were 28 males and 36 females, 3 of them were children (4.7%). Mean age was 54.2 years (range 15-77). Two types of Gore-Tex prosthesis were used: Diastat and Stretch. All grafts were implanted in the upper extremities. Kaplan-Meier survival curves were calculated to determine primary and secondary patency. Log-rank analysis was used to determine differences between curves. Results: Primary and secondary patency at 12 months was 52.5% and 67.5%, and at 18 months respectively 41.5% and 58.2%. The Diastat graft had a lower primary and secondary patency compared with the Stretch graft (respectively p = 0.02 and p = 0.008). Factors such as gender, coexisting diabetes and hypertension did not determine graft patency. Thrombosis was one of the most frequent complications. The remaining complications included stenosis, pseudoaneurysms, infection, steal syndrome and seroma. Conclusion: On the basis of our experience Stretch grafts appear a better option for creating vascular access for HD than Diastat grafts.     

The role the type of vascular access plays in the transmission of hepatitis C virus in a high prevalence hemodialysis unit

Background: The necessity of having a vascular access site as well as extracorporeal blood circulation, may add to the risk for patients being dialyzed in units with high HCV prevalence of acquiring hepatitis C virus (HCV) infection. This study endeavors to determine the role the type of vascular access plays in the transmission of HCV infection in the hemodialysis (HD) unit of a Middle Eastern country. Methods: The records of 198 patients with end-stage renal disease (ESRD) enrolled on maintenance HD from November 1995 to November 2000 at this tertiary care center, were retrospectively reviewed to match the HCV prevalence and seroconversion rates among patients groups being dialyzed through various types of vascular accesses. Factors such as, number of units of blood transfused and dialytic age (time-span since the initiation of the HD treatment), implicated in transmission of HCV infection in HD units, were also recorded, and compared among these cohorts. Results: The overall, high HCV seroprevalence of 43.4% (86/198) and annual seroconversion rate of 8.6% per year were recorded. Patients with arteriovenous fistula (AVF) documented peak anti-HCV prevalence [61.7% (63/102)] and annual seroconversion rates (12.3%) as compared to lowest prevalence of 12.9% (4/34) and seroconversion rate of 2.5%, observed among patients with permanent Catheters (PC). Patients dialyzed through polytetrafluoroethylene (PTFE) grafts recorded the next highest HCV prevalence of 47.8% (11/23) with seroconversion rate of 9.5% but temporary catheter (TC) group had HCV prevalence of 19% (8/42) and seroconversion rate of 3.8% [Odd Ratio (OR)-1.58, 95% Confidence Interval (CI) (0.37-7.12), p-NS]. Conclusions: Considerably higher annual seroconversion rates in AVF [OR-10.90, 95% CI (3.2-40.0), p<0.0001] and PTFE [OR-5.71, 95% CI (1.31-26.79), p<0.016)] groups, appear to suggest that the patients being dialyzed through AVF and PTFE, carried significantly higher risk of acquisition of HCV infection compared to those dialyzed through TC and PC (reference group). This could possibly be attributed to likely accessibility of HCV to blood circulation due to possible breakdown of standard infection control precautions during repeated punctures and cannulations of AVF and PTFE to perform a HD, in a unit with high baseline HCV prevalence.     

Difficult vascular access in patients with end-stage renal failure

BACKGROUND/AIM: End-stage renal failure patients requiring long-term hemodialysis need a durable vascular access. The arteriovenous fistula (AVF) with its long patency rate and low complication profile is usually the first choice for vascular access creation. However, when superficial veins are not suitable for AVF creation or all have been exhausted as a result of repeated AVF procedures, arteriovenous grafts (AVGs) using expanded polytetraflouroethylene (ePTFE) is an alternative. This study reviewed our experience in using PTFE AVGs for vascular access in patients requiring chronic hemodialysis. MATERIALS AND METHODS: In a prospective study, from September 2002 to October 2004, 21 PTFE AVGs were placed in 21 patients. We evaluated the complications and patency. RESULTS: There were 12 female and nine male patients of mean age 58+/-8.7 years (range=45 to 76 years). Nine patients (43%) had hypertensive nephrosclerosis, 6 (29%) diabetic, 2 (10%) glomerulonephritis, 3 (14%) systemic lupus erythematosis requiring long-term steroids, and 1 (4.7%) unknown cause. The patency rate at 24 months was 85.7%. Complications included graft thrombosis (three; 14.3%), wound infection (three; 14.3%) and graft infection (one; 4.8%). CONCLUSION: ePTFE AVGs offer reasonable patency and serviceability rates as a vascular access modality, but in view of their complication profile, the native vein arteriovenous fistula should continue to be the first choice for vascular access for patients requiring chronic hemodialysis.     

Vascular access use in Europe and the United States: results from the DOPPS.

BACKGROUND: A direct broad-based comparison of vascular access use and survival in Europe (EUR) and the United States (US) has not been performed previously. Case series reports suggest that vascular access practices differ substantially in the US and EUR. We report on a representative study (DOPPS) which has used the same data collection protocol for> 6400 hemodialysis (HD) patients to compare vascular access use at 145 US dialysis units and 101 units in five EUR countries (France, Germany, Italy, Spain, and the United Kingdom). METHODS: Logistic analysis evaluated factors associated with native arteriovenous fistula (AVF) versus graft use or permanent access versus catheter use for prevalent and incident HD patients. Times to failure for AVF and graft were analyzed using Cox proportional hazards regression. RESULTS: AVF was used by 80% of EUR and 24% of US prevalent patients, and was significantly associated with younger age, male gender, lower body mass index, non-diabetic status, lack of peripheral vascular disease, and no angina. After adjusting for these factors, AVF versus graft use was still much higher in EUR than US (AOR=21, P < 0.0001). AVF use within facilities varied from 0 to 87% (median 21%) in the US, and 39 to 100% (median 83%) in EUR. For patients who were new to HD, access use was: 66% AVF in EUR versus 15% in US (AOR=39, P < 0.0001), 31% catheters in EUR vs. 60% in US, and 2% grafts in EUR vs. 24% in US. In addition, 25% of EUR and 46% of US incident patients did not have a permanent access placed prior to starting HD. In EUR, 84% of new HD patients had seen a nephrologist for> 30 days prior to ESRD compared with 74% in the US (P < 0.0001); pre-ESRD care was associated with increased odds of AVF versus graft use (AOR=1.9, P=0.01). New HD patients had a 1.8-fold greater odds (P=0.002) of starting HD with a permanent access if a facility's typical time from referral to access placement was < or =2 weeks. AVF use when compared to grafts was substantially lower (AOR=0.61, P=0.04) when surgery trainees assisted or performed access placements. When used as a patient's first access, AVF survival was superior to grafts regarding time to first failure (RR=0.53, P=0.0002), and AVF survival was longer in EUR compared with the US (RR=0.49, P=0.0005). AVF and grafts each displayed better survival if used when initiating HD compared with being used after patients began dialysis with a catheter. CONCLUSION: Large differences in vascular access use exist between EUR and the US, even after adjustment for patient characteristics. The results strongly suggest that a facility's preferences and approaches to vascular access practice are major determinants of vascular access use.     

Statins are independently associated with reduced mortality in patients undergoing infrainguinal bypass graft surgery for critical limb ischemia

OBJECTIVE: Evidence suggesting a beneficial effect of cardioprotective medications in patients with lower extremity atherosclerosis derives largely from secondary prevention studies of heterogeneous populations. Patients with critical limb ischemia (CLI) have a large atherosclerotic burden with related high mortality. The effect of such therapies in this population is largely inferred and unproven. METHODS: The Project of Ex-Vivo vein graft Engineering via Transfection III (PREVENT III) cohort comprised 1404 patients with CLI who underwent lower extremity bypass grafting in a multicenter, randomized prospective trial testing the efficacy of edifoligide for the prevention of graft failure. Propensity scores were used to evaluate the influence of statins, beta-blockers, and antiplatelet agents on outcomes while adjusting for demographics, comorbidities, medications, and surgical variables that may influence drug use. Primary outcomes were major adverse cardiovascular events < or =30 days, vein graft patency, and 1-year survival assessed by Kaplan-Meier method. Potential determinants of 1-year survival were modeled using a multivariate Cox regression. RESULTS: In this cohort, 636 patients (45%) were taking statins, 835 (59%) were taking beta-blockers, and 1121 (80%) were taking antiplatelet drugs. Perioperative major adverse cardiovascular events (7.8%) and early mortality (2.7%) were not measurably affected by the use of any drug class. Statin use was associated with a significant survival advantage at 1 year of 86% vs 81% (hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.52-0.98; P = .03) by analysis of both unweighted and propensity score-weighted data. Use of beta-blockers and antiplatelet drugs had no appreciable impact on survival. None of the drug classes were associated with graft patency measures at 1 year. Significant predictors of 1-year mortality by Cox regression modeling were statin use (HR, 0.67; 95% CI, 0.51-0.90; P = .001), age >75 (HR, 2.1; 95% CI, 1.60-2.82; P = .001), coronary artery disease (HR, 1.5; 95% CI, 1.15-2.01; P = .001), chronic kidney disease stages 4 (HR, 2.0; 95% CI, 1.17-3.55; P = .001) and 5 (HR, 3.4; 95% CI, 2.39-4.73; P < .001), and tissue loss (HR, 1.9; 95% CI, 1.23-2.80; P = .003). CONCLUSIONS: Statin use is associated with improved survival in CLI patients 1 year after surgical revascularization. Further studies are indicated to determine optimal dosing in this population and to definitively address the question of relationship to graft patency. These data add to the growing literature supporting statin use in patients with advanced peripheral arterial disease.     

Remarks on Surgical Strategy in Creating Vascular Access for Hemodialysis: 18 Years of One Center’s Experience

The aim of the study is to evaluate surgical methods for creating vascular access for hemodialysis (HD) in patients with chronic renal failure. Over the last 18 years, 1,827 surgical procedures were performed in 722 patients (399 men and 323 women, mean age 43.7 ± 17 years) in order to provide and maintain permanent vascular access for HD. Among all the surgical procedures, 992 were based on the construction of arteriovenous fistulas (AVF) and 835 were undertaken as secondary reparative surgical procedures. A total of 992 vascular accesses have been performed, including 904 AVF on upper and 14 on lower extremities as well as insertion of 74 permanent catheters. Radiocephalic AVF (RCAVF) was the principal type of AVF (58.8%). While constructing secondary angio-access after using RCAVF on the other extremity, fistulas with usage of brachial vessels were preferred. A total of 228 AVF of this type were created, including 143 brachiocephalic (BCAVF) and 85 brachiobasilic (BBAVF) AVF. Lately, synthetic grafts (arteriovenous graft, AVG) have been used more frequently, in 90 AVF. A brachial straight graft was the main type procedure performed, with polytetrafluoroethylene (95.6%). The patency of the fistulas has been evaluated. Kaplan-Meier survival curves were calculated to determine primary, primary-assisted, and secondary patency. Log-rank analysis was used to determine differences between curves. Primary, primary-assisted, and secondary patency at 12 months and 24 months were calculated. Comparing AVF patency in two patients’ age periods (18-65 years, >65 years), it may be concluded that in the elderly group AVG provides better treatment for AVF. Finally, we conclude that a multidisciplinary approach to vascular access strategy offers the best option to achieve good functional AVF. Autogenous arteriovenous access should be regarded as the most suitable type in creating VA. However, individual conditions should be taken into consideration.This work was published in part in abstract form (3rd International Congress of the Vascular Access Society, Lisbon, Portugal, 2003).     

Redo bypass surgery to the infrapopliteal arteries for critical leg ischaemia.

OBJECTIVES: to evaluate the results of redo bypass surgery to the infrapopliteal artery and the value of adjuvant arteriovenous fistula (AVF) in this setting. DESIGN: retrospective study. MATERIALS: fifty-one redo reconstructions to the infrapopliteal arteries were done for critical leg ischaemia in 45 patients who have had primary infrainguinal reconstructions to the popliteal artery in 20 cases (39%), the crural arteries in 18 (35%), and the pedal arteries in 13 (25%). METHODS: a PTFE prosthesis was used in 21 cases (41%). A Miller cuff was used in 16 prosthetic grafts. Adjuvant AVF was added to three autogenous vein and 12 prosthetic grafts. RESULTS: at 2 years, the primary patency rate was 42%, the secondary patency was 43%, the limb salvage was 67%, the survival was 77%, and 53% of patients were alive with salvaged leg. The primary patency rate with a vein graft was 44% at 1 year, with prosthesis plus AVF 67%, but with prosthesis without AVF only 19%. Secondary patency rates were similar. Prosthetic graft with AVF and those without AVF achieved a 1-year leg salvage rate of 100% and 51%, respectively (p =0.01). Patients with adjuvant AVF had a worse 2-year survival rate that those without AVF (31% vs 89%) (p =0.007; RR: 8.87, CI 95%: 1.62-48.42). CONCLUSIONS: redo bypass surgery using autogenous vein graft may achieve satisfactory long-term results. The use of adjuvant AVF may improve patency of redo infrapopliteal prosthetic bypass grafts.     

Patients undergoing infrainguinal bypass to treat atherosclerotic vascular disease are underprescribed cardioprotective medications: effect on graft patency, limb salvage, and mortality

INTRODUCTION: Established American Heart Association guidelines recommend the use of statin drugs, angiotensin converting enzyme (ACE) inhibitors, and antiplatelet agents in patients with systemic atherosclerosis, such as those undergoing operative intervention to treat peripheral atherosclerotic disease. Many of these patients have not received treatment of coronary heart disease and have not been prescribed these medications. Whether statin drugs and ACE inhibitors confer an improvement in graft patency, limb salvage, and operative mortality is unknown. METHODS: Consecutive patients who underwent infrainguinal bypass between 1997 and 2002 were evaluated for demographic data, comorbid disease, medication use, as well as cumulative graft patency, limb salvage, and mortality. Univariate, multivariate logistical regression, and Kaplan-Meier analyses were performed. P <.05 was considered significant. RESULTS: Two hundred ninety-three patients (mean age, 64 years; 67% men) underwent 338 infrainguinal bypass procedures with autologous vein (n = 218), prosthetic grafts (n = 88), or composite prosthetic-vein grafts (n = 32). Limb salvage was the operative indication in 75% of procedures. Coexisting diseases included hypertension (70%), diabetes (52%), hyperlipidemia (37%), coronary heart disease (51%), congestive heart failure (14%), and active tobacco use (30%). Statin drugs were taken by 56% of patients, ACE inhibitors by 54% of patients, and antiplatelet agents or warfarin sodium (Coumadin) by 93% of patients. Postoperative graft surveillance was done in 39% of patients. Cumulative graft patency was 73%, limb salvage was 85%, and mortality was 9%, with a mean follow-up of 17 months.Factors independently associated with increased graft patency included statin drug use (odds ratio [OR], 3.7; 95% confidence interval [CI], 2.1-6.4), male sex (OR, 2.8; 95% CI, 1.6-5.0), and graft surveillance (OR, 2.4; 95% CI, 1.3-4.5). Factors associated with decreased amputation rate were statin drug use (OR, 0.34; 95% CI, 6.15-0.77) and graft surveillance (OR, 0.23; 95% CI, 6.1-0.63). Factors associated with decreased mortality included graft surveillance (OR, 0.18; 95% CI, 0.1-0.56), whereas congestive heart failure (OR, 6.5; 95% CI, 2.5-17) and hemodialysis-dependent renal failure (OR, 29; 95% CI, 6.1-140) were associated with increased mortality. Kaplan-Meier analysis showed that only ACE inhibitors were associated with lower mortality (P =.05) CONCLUSIONS: Patients undergoing infrainguinal bypass are undertreated with respect to cardioprotective medications. ACE inhibitor use is associated with lower mortality, and statin drug use is associated with improved graft patency and limb salvage. Institution of consensus guidelines concerning these medications should be considered by all vascular specialists, including vascular surgeons.     

Fluoropolymer-coated dacron versus PTFE grafts for femorofemoral crossover bypass: randomised trial.

OBJECTIVES: To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery. DESIGN: A randomised multicentre clinical trial comparing two vascular grafts with participation of 10 departments of vascular surgery in Denmark, Sweden and Norway. PATIENTS AND METHODS: 198 patients were randomised to PTFE (n=107) or fluoropolymer-coated Dacron grafts (n=91), 63% underwent surgery for claudication, 27% for ischaemic rest pain and 10% for tissue loss. The median follow-up time was 24 months (IQR 19-26 months). RESULTS: The primary patency rate of the two grafts was similar (log rank test: p=0.35). The primary patency rates (95% CI) for coated Dacron and PTFE grafts were 92% (86-98) and 94% (89-99) at 12 months and 87% (74-95) and 93% (87-99) at 24 months, respectively. CONCLUSION: In patients with unilateral iliac artery disease not amenable to angioplasty, the femoral-femoral bypass is durable and effective. No difference in patency was found between the two graft materials (fluoropolymer coated Dacron and PTFE).     

PTFE Grafts Versus Tunneled Cuffed Catheters for Hemodialysis: Which Is the Second Choice When Arteriovenous Fistula Is Not Feasible?

Vascular access‐related complications are still one of the leading causes of morbidity in hemodialysis patients. The aim of this study was to compare polytetrafluoroethylene (PTFE) grafts versus tunneled cuffed permanent catheters (TCCs) in terms of vascular access and patients' survival. An observational study was carried out with a 2‐year follow‐up. Eighty‐seven chronic hemodialysis patients were enrolled: 31 with a PTFE graft as vascular access for hemodialysis versus 56 with a TCC. Patients' mean age was 63.8 ± 14.6 (grafts) versus 73.5 ± 11.3 years (TCCs), P = 0.001. Significantly more patients with TCC had atrial fibrillation than patients with grafts (30.3% versus 6.5%, P = 0.01). In an unadjusted Kaplan–Meier analysis, median TCC survival at 24 months was 5.4 months longer than that of PTFE grafts but not significantly (log‐rank test = 1.3, P = ns). In a Cox regression analysis adjusted for age, gender, number of previous vascular accesses, diabetes, atrial fibrillation, smoking, and any complication, this lack of significant difference in survival of the vascular access between TCC and PTFE groups was confirmed and diabetes proved to be an independent risk factor for the survival of both vascular accesses considered (P = 0.02). In an unadjusted Kaplan–Meier analysis, a higher mortality was found in the TCC group than in the PTFE group at 24 months (log‐rank test = 10.07, P < 0.01). The adjusted Cox regression analysis showed that patients with TCC had a 3.2 times higher risk of death than patients with PTFE grafts. When an arteriovenous fistula (AVF) is not possible, PTFE grafts can be considered the vascular access of second choice, whereas TCCs can be used when an AVF or PTFE graft are not feasible or as a bridge to AVF or PTFE graft creation.     

Determinants of type and timing of initial permanent hemodialysis vascular access

BACKGROUND: We undertook a population-based study of hemodialysis (HD) patients to determine which factors are important in predicting the type of permanent access initially placed and if a functional permanent access is in place at the start of HD. METHODS: Selected characteristics were abstracted from the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Study (DMMS) Wave 2. Logistic regression was used to estimate the independent contribution of specific characteristics in predicting whether the initial permanent access placed was an arteriovenous (AV) fistula compared with a polytetrafluoroethylene (PTFE) graft, and in predicting whether permanent access (fistula or graft) was in place at the initiation of dialysis. RESULTS: Sixty-seven percent of the patients had an AV graft placed as their first permanent access. Characteristics important in predicting if a fistula was initially placed included age (per decade; aOR = 0.84, P < 0.001), female gender (aOR = 0.52, P < 0.001), body mass index (per standard deviation; aOR = 0.70, P = 0.09), avoiding blood draws (aOR = 1.96, P < 0.001), ability to ambulate (aOR = 2.24, P = 0.008), underlying renal disease (glomerular compared with diabetes, aOR = 2.19, P = 0.009), college education (aOR = 1.72, P = 0.002), and sharing in decision making (aOR = 1.50, P = 0.02). Thirty-four percent of patients (34.4%) had functional permanent access at the start of HD. Characteristics important in predicting which patients had functional permanent access included serum albumin (per 1 mg/dL increase, aOR =1.55, P = 0.003), erythropoietin prior to starting HD (aOR = 1.79, P = 0.002), fewer predialysis nephrologist visits (aOR = 0.21, P < 0.001), and when the patient was told they had renal disease (aOR = 0.33, P = 0.002). CONCLUSIONS: PTFE grafts were the most common initial permanent access. The majority of patients did not have permanent access at the start of dialysis. Factors that are thought to compromise identification of adequate veins were important predictors of PTFE graft placement. Permanent access at the start of HD was largely a function of early patient education and early referral to a nephrologist.     

Haemodialysis dose is independent of type of surgically-created vascular access

Background: In the United States, the use of polytetraflourotheylene (PTFE) graft compared with native arteriovenous fistula (AVF) for haemodialysis vascular access has been increasing despite a greater than two-fold higher incidence of thrombosis and infection associated with PTFE grafts. Methods: We studied 214 haemodialysis patients with not more than two revisions of their vascular access, to determine whether any relationship exists between the type of haemodialysis vascular access and dialysis dose assessed primarily by urea reduction ratio (per cent reduction in blood urea nitrogen concentration after a dialysis session). Serum albumin concentration was used as a secondary outcome measure of dialysis adequacy. Urea reduction ratio and predialysis serum albumin concentration were measured at onset of study and at 4-week intervals and mean values were calculated for each subject. Results: The 214 patients (118 males, 96 females) included 173 Blacks (81%), 26 Whites (15%), and 15 Hispanics (7%), of mean (±SD) age 55.6±15.5 years. Of these 214 subjects, 111 (52%) had a native AVF, while 103 (48%) had a PTFE graft. Both mean urea reduction ratio (native AVF=69±6.7% vs PTFE graft=70±7.3%; P=0.31), and mean serum albumin concentration (native AVF=4.02±0.39 g/dl vs PTFE graft=4±0.33 g/dl; P=0.59) were equivalent in both groups. Separate multiple logistic regression analyses with type of vascular access as one of the independent variables, found no significant relationship between type of vascular access and either a urea reduction ratio >65% (P=0.67), or a serum albumin concentration >4 g/dl (P=0.89), after adjustment for age of vascular access, access revision, location of access, dialyser urea clearance, length of dialysis treatment, body weight, and age. Conclusion: We conclude that PTFE grafts do not permit delivery of better dialysis than native AVF. The increasing use of PTFE grafts in the United States does not have any clinical justification.     

The role of initial hemodialysis vascular access in the outcome of subsequent kidney transplantation

The role of initial hemodialysis vascular access in the subsequent kidney transplant outcome is unclear. Study population was derived from the United States Renal Data System and included adult patients with end‐stage renal disease who started HD 1/1/2005–9/1/2009 and subsequently received at least one kidney transplant. Primary outcome variables were death‐censored graft loss and all‐cause recipient mortality. Among the study population (n = 17 157), 12 428 (72.4%) patients were initiated on HD with a catheter, 4090 (23.8%) patients with an arterio‐venous fistula (AVF), and 639 (13.7%) patients with an arterio‐venous graft (AVG). The rate of death‐censored kidney allograft loss in AVF and AVG groups was not significantly different from the catheter group (HR, 0.82; p = 0.07 and HR, 0.68; p = 0.13, respectively). All‐cause mortality of patients initiated on HD with AVG (HR, 0.761; p = 0.21) was not significantly different compared to those with catheters. However, all‐cause mortality in the AVF group was lower compared to patients initiated on HD with catheters (HR, 0.65; p = 0.001). AVF used at the initiation of HD was associated with lower rate of all‐cause mortality after kidney transplantation compared to the catheter. The type of initial vascular access for hemodialysis was not associated with kidney allograft survival.     

Arteriovenous fistula outcomes in the era of the elderly dialysis population

BACKGROUND: The growth of patients > or =65 years on hemodialysis is increasing. Guidelines recommend arteriovenous fistula (AVF) access but their outcomes in elderly patients are controversial. This study compared the outcomes of AVF in patients <65 years old (65- group) versus those > or =65 years old (65+ group). METHODS: This retrospective analysis of prospectively collected data included 444 incident, first-time AVF created in a large dialysis center between January 1, 1995 and July 1, 2003. The primary outcome of AVF cumulative patency was evaluated using Kaplan-Meier survival analysis with log-rank test comparison. A Cox model determined factors associated with AVF loss. RESULTS: One hundred ninety-six patients (44%) were in the 65+ group. In total, there were 230 (52.2%) radiocephalic, 186 (42.2%) brachiocephalic, and 25 (5.6%) basilic vein transposed AVF. The one-year AVF cumulative survival was 75.1% (65+ group) and 79.7% (65- group); the five-year survival was 64.7% (65+ group) and 71.4% (65- group). The overall total procedure, angioplasty, thrombolysis, and revision rates per access-year were 0.83, 0.30, 0.66, and 0.16, respectively. The 65+ group had a relative risk of 1.7 of their AVF failing to mature compared with the 65- group. Multivariate analysis yielded these variables significant for AVF loss: male sex HR 0.63 (95% CI 0.44-0.91), coronary artery disease HR 2.1 (95% CI 1.5-3.0), and Caucasian ethnicity HR 0.63 (95% CI 0.44-0.91). CONCLUSION: Age should not be a limiting factor when determining candidacy for AVF creation due to equivalent survival and procedural rates. Failure of fistula maturation is a primary concern to patients of all ages and demands further study.     

Arteriovenous Fistula Placement in the Elderly: When Is the Optimal Time?

Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis (HD). However, many AVFs fail before starting dialysis. To assess the optimal time for AVF placement in the elderly, we linked data from the US Renal Data System with Medicare claims data to identify 17,511 patients≥67 years old on incident HD who started dialysis between January 1, 2005, and December 31, 2008, with an AVF placed as the first predialysis access. AVF success was defined as dialysis initiation using the AVF, with time between AVF placement and dialysis start as our primary variable of interest. The mean age was 76.1±6.0 years, and 58.3% of subjects were men. Overall, 54.9% of subjects initiated dialysis using an AVF, and 45.1% of subjects used a catheter or graft. The success rate increased as time from AVF creation to HD initiation increased from 1–3 months (odds ratio [OR], 0.49; 95% confidence interval [95% CI], 0.44 to 0.53) to 3–6 months (OR, 0.93; 95% CI, 0.85 to 1.02) to 6–9 months (OR, 0.99; 95% CI, 0.88 to 1.11) but stabilized after that time. Furthermore, the number of interventional access procedures increased over time starting at 1–3 months, with a mean of 0.64 procedures/patient for AVFs created 6–9 months predialysis compared with 0.72 for AVFs created >12 months predialysis (P<0.001). Although limited by the observational nature of this study, our results suggest that placing an AVF>6–9 months predialysis in the elderly may not associate with a better AVF success rate.     

Pre‐existing Arterial Micro‐Calcification Predicts Primary Unassisted Arteriovenous Fistula Failure in Incident Hemodialysis Patients

Vascular access micro‐calcification is a risk factor for cardiovascular morbidity and mortality in hemodialysis (HD) patients but its influence on vascular access patency is still undetermined. Our study aimed to determine the impact of arterial micro‐calcification (AMiC) on the patency of vascular access in HD patients. One‐hundred fourteen HD patients receiving arteriovenous fistula (AVF) operation were included in this study. During the operation, we obtained partial arterial specimen and performed pathological examination by von Kossa stain to identify AMiC. We compared primary unassisted AVF failure within 1 year between positive and negative AMiC groups, and performed Cox regression analysis for evaluating risk factor of AVF failure. The incidence of AMiC was 37.7% and AVF failure occurred in 45 patients (39.5%). The AVF failure rate within 1 year was greater in the positive AMiC group than those in the negative AMiC group (53.5% vs. 31.0%, p = 0.02). Kaplan–Meier analysis showed that the positive AMiC group had a lower AVF patency rate than the negative AMiC group (p = 0.02). The presence of AMiC was an independent risk factor for AVF failure. In conclusion, preexisting AMiC of the vascular access is associated with primary unassisted AVF failure in incident HD patients.     

Cardiovascular comorbidity and late referral impact arteriovenous fistula survival: a prospective multicenter study

Autologous arteriovenous fistulas (AVF) have the best 5-yr patency and the lowest complication rate among hemodialysis vascular accesses. However, maturation requirements to optimize survival are unknown. A longitudinal cohort study was conducted to ascertain risk factors for failure, maturation time, and survival of the first AVF. All patients who initiated hemodialysis between January 1, 1997, and December 31, 2002, in three centers were included in this study. Analysis was restricted to patients who received an AVF. Cox regression was used to estimate the association between predictors of interest and primary and secondary AVF survival. Of the 535 patients enrolled (mean age, 66.5 yr; 57.8% male; 26.7% diabetic), 513 (96%) received an AVF. Patients who initiated with catheters (47%) cannulated their AVF earlier (median maturation period, 0.78 versus 1.80 mo; P < 0.001). Median primary and secondary survivals were longer than 50 and 72 mo, respectively. After adjustment for confounding factors, cardiovascular disease (hazard ratio [HR], 1.84; 95% confidence interval [CI], 1.26 to 2.67), utilization earlier than 1 mo after placement (HR, 1.94; 95% CI, 1.34 to 2.82), and referral within 3 mo of dialysis start (HR, 1.55; 95% CI, 1.04 to 2.32) were associated with a reduction in primary AVF survival. Presence of cardiovascular disease (HR, 2.21; 95% CI, 1.38 to 3.55), maturation time <15 d (HR, 2.12; 95% CI, 1.20 to 3.73), and presence of catheters at hemodialysis initiation (HR, 1.79; 95% CI, 1.13 to 2.84) were associated with lower secondary AVF survival. It is concluded that cardiovascular disease, late referral, temporary catheters, and early cannulation are associated with impaired AVF survival. It is recommended that AVF be allowed to mature at least 1 mo before cannulation.     

The Effect of Buttonhole Cannulation vs. Rope‐ladder Technique on Hemodialysis Access Patency

The rope‐ladder (RL) technique is the most common technique used for cannulation of arteriovenous fistulae (AVF). Buttonhole cannulation (BHC), or constant‐site technique, is recommended by the National Kidney Foundation's Kidney Disease Outcome Quality Initiative (NKF/KDOQI) vascular access guidelines. We compared outcomes of primary patency, episodes of bacteremia, access blood flow (Qa), and quality of life (QoL) scores between RL and BHC patients. Using a prospectively collected, vascular access database, a total of 45 prevalent dialysis patients using BHC were compared with 38 patients using the RL technique over a median of 12 months (inter‐quartile range: 4–27 months). The two groups did not differ significantly in demographics except that diabetes was more common in those using BHC as compared to rope‐ladder (69% vs. 34%; p = 0.002). Risk factors associated with lack of primary patency were age (hazards ratio [HR] = 1.02 per decade; 95% CI: 1.00–1.03; p = 0.04) and female gender (HR = 1.92; 95% CI: 1.08–3.40; p = 0.03). Use of the buttonhole technique was not associated with improved primary patency (HR = 1.22, 95% CI: 0.65–2.28; p = 0.53). Episodes of bacteremia and mean scores from KDQOL‐36 did not differ significantly between the groups. This study demonstrates for the first time that BHC use is not associated with improved access patency.