Some old drugs improve late primary patency rate of native arteriovenous fistulas in hemodialysis patients

Analysis of predictive factors of thrombosis in autogenous arteriovenous fistula

PURPOSE

To investigate the predictors of early diagnosis of thrombus of autogenous arteriovenous fistula (aAVF).

METHODS

The included patients were divided into the thrombus group with aAVF failure or thrombosis and the control group with good internal fistula function. The general data of the patients, including age, sex, diabetes mellitus, were collected. Platelets (PLT), platelet crit (P-LCR), platelet distribution width (PDW), mean platelet volume (MPV), homocysteine (HCY), and other biochemical data were collected. The predictors of thrombus of aAVF were obtained by the t test and logistic regression analysis, and receiver operating characteristic (ROC) curve analysis was used to compare the area under the ROC curve (AUC) between the combined predictors and the original indicators. The optimal critical value was determined when the Youden index reached its maximum value, and the sensitivity, specificity, accuracy, diagnostic index, and so on were calculated. Finally, prediction was performed by substituting each value in individually.

RESULTS

PLT, PDW, P-LCR, MPV, and HCY showed significant differences between two groups (p < 0.05). Logistic regression analysis showed that, for PLT (OR = 1.014, 95% CI 1.006-1.022, p = 0.01), PDW (OR = 1.295, 95% CI 1.009-1.661, p = 0.042), P-LCR (OR = 1.230, 95% CI 1.089-1.389, p = 0.001), MPV (OR = 1.696, 95% CI 1.101-2.613, p = 0.017), and HCY (OR = 1.332, 95% CI 1.182-1.502, p = 0.01), the difference was significant; PLT, PDW, P-LCR, MPV, and HCY were positively correlated with thrombogenesis (p < 0.05). By logistic regression, a group of the five predictors of PLT, PDW, P-LCR, MPV, and HCY was obtained, and the combined predictors were 0.014*PLT + 0.258*PDW + 0.207*P-LCR + 0.528*MPV + 0.287*HCY. The area under the curve of the combined predictor was 0.933, the sensitivity was 92.4%, the specificity was 81.2%, the maximum diagnostic index was 0.736, the diagnostic cutoff point was 21.790, and the accuracy rate was 87%.

CONCLUSION

PLT, PDW, P-LCR, MPV, and HCY are predictors of thrombus of aAVF. They can better predict thrombus of aAVF, and the combination of these five indicators is better than a single indicator.

Anticoagulation Therapy is Associated with Increased Access-related Wound Infections after Hemodialysis Access Creation

BACKGROUND

The effect of anticoagulation therapy (AC) on hemodialysis access patency and related complications is not well defined. Patients on long-term or chronic AC due to their underlying comorbid conditions may be particularly susceptible to access-related bleeding and complications from repetitive cannulation. Our goal is to assess the effect of anticoagulation therapy on outcomes after access creation.

METHODS

The Vascular Quality Initiative (VQI) database was queried for patients undergoing arteriovenous fistula (AVF) or graft (AVG) placement, from 2011 to 2019. Only patients with data on post-procedural AC status were included. Anticoagulation use was defined as patients on warfarin, dabigatran, or rivaroxaban after access creation at postoperative follow up. Demographic and procedural details were analyzed. Wound infection and patency rates at six months were assessed. Binomial logistic regression analysis was performed to assess the association of anticoagulation use with these outcomes.

RESULTS

A total of 27,757 patients underwent access creation, with the majority undergoing AVF creation (78.8%). The average age was 61.4 years and 55.3% were male. 12.9% of patients were on postoperative AC. The wound infection rate was 2.3- 3.8% in the no AC and AC cohorts, respectively (P < 0.001). At six months follow-up, patency was 85.7- 84.3% in the no AC and AC cohorts, respectively (P = 0.044). Expectedly, grafts had lower patency rates compared to AVF; those within the no AC cohort had a patency of 83.0% compared to 81.2 % in those on AC (P = 0.106). On multivariable analysis, anticoagulation use was associated with a higher risk of wound infections (odds ratio [OR] 1.513, 95% confidence interval [CI] 1.160-1.973, P = 0.002). AC use did not significantly affect access patency.

CONCLUSION

Anticoagulation therapy was associated with a higher rate of wound infections but did not affect short-term access patency within six-months. These patients warrant close surveillance of their access for signs of infection. Furthermore, long-term implications of anticoagulation needs further evaluation.

Role of Doppler ultrasonography in the evaluation of hemodialysis arteriovenous access maturation and influencing factors

The goal of vascular access creation is to achieve a functioning arteriovenous fistula (AVF) or arteriovenous graft (AVG). An autologous fistula has been shown to be superior to AVG or to central venous catheters (CVCs) with lowest rate of re-intervention, but vessel obstruction or immaturity accounts for 20 % to 54% of cases with primary failure of AVF. This review is focused on the factors influencing maturation; indication and timing of preoperative mapping/creation of vascular access; ultrasound parameters for creation AVF/AVG; early postoperative complications following creation of a vascular access; ultrasound determinants of fistula maturation and endovascular intervention in vascular access with maturation failure. However, vascular accesses that fail to develop, have a high incidence of correctable abnormalities, and these need to be promptly recognized by ultrasonography and managed effectively if a high success rate is to be expected. We review approaches to promoting fistula maturation and duplex ultrasonography (DUS) of evaluating vascular access maturation.

Statins Protect against Thrombosis of Cannulated Radiocephalic Fistulas in Diabetic Patients

BACKGROUND

Radiocephalic arteriovenous fistula (RCAVF) creation is the preferred first line hemodialysis access procedure. Analysis of diabetic rat arteriovenous fistula model indicates improved vascular function with HMG-CoA-Reductase Inhibitor (statin) use. We predict similar outcomes in diabetic patients undergoing primary RCAVF placement.

METHODS

A Veterans Administration Hospital dialysis access database over a 15-year period was queried identifying all RCAVF placements in diabetic patients. Patients were stratified into statin medication usage or not at RCAVF creation. Outcomes examined include rate of successful cannulation, functional patency duration, interventions per access, and rates of access thrombosis. Thrombosis-free survival of cannulated RCAVFs were compared using Kaplan-Meier method with log-rank analysis followed by univariate, stepwise logistic regression and ROC curve analysis.

RESULTS

Total number of 123 RCAVF cases were performed in 122 diabetic male patients. At the time of RCAVF placement, 92 cases were performed on patients that were taking statin medication and 31 cases were performed on patients that were not taking statin medication. There was no difference in terms of rate of successful cannulation, functional patency duration, and number of interventions per access between the statin and non-statin groups. However, rate of RCAVF thrombosis once accessed was significantly lower in the statin group compared to the non-statin group (P = 0.0005). Kaplan-Meier survival curve for each group were compared using log-rank test to reveal that diabetic patients who were on statin therapy at the time of operation had significantly higher access survival over time against thrombosis once it was cannulated for dialysis treatment compared to those who were not on statin therapy (P = 0.0003). Univariate, stepwise logistic regression model indicated statin use as the only significant factor associated with lack of thrombosis (P = 0.05).

CONCLUSIONS

Statins appear to have protective effects against RCAVF thrombosis as predicted in animal models for diabetic patients undergoing primary RCAVF placements. There were similar functional outcomes in terms of rate of successful cannulation, functional patency duration, and number of interventions per access. These data should encourage further investigation of statins and their role in hemodialysis access.

Effects of cardiovascular medications on primary patency of hemodialysis arteriovenous fistula

While the patency of vascular access is essential for hemodialysis patients, optimal pharmaceutical treatment to maintain arteriovenous fistula (AVF) patency remains lacking. As cardiovascular diseases are highly prevalent in patients with end-stage renal disease, various cardiovascular medications have also been used to maintain AVF patency. However, previous studies revealed inconsistent therapeutic effects and a comprehensive evaluation of this issue is needed. The present retrospective, longitudinal cohort study included patients receiving successful AVF creation. The evaluated cardiovascular medications included antiplatelet agents, antihypertensive agents, nitrates and nitrites, statins, dipyridamole, and pentoxifylline. The outcome was AVF primary patency. All laboratory data and medication profiles were recorded at baseline and followed at 3-month interval, until the end of the 2-year study period. Cox proportional regression model with time-dependent covariates was used to evaluate the risk for AVF patency loss. A total of 349 patients were included in the present study, in which 57% were men and the mean age was 65 ± 14 years. Among the included patients, 40% used antiplatelet agents, 27% used dipyridamole and 36% used statins at baseline. Of all the evaluated cardiovascular medications, only dipyridamole showed significant association with a higher risk for loss of AVF patency. To evaluate the effect of combination of antiplatelet agents and dipyridamole, the patients were classified into four groups, I: combine use of antiplatelet agents and dipyridamole, II: antiplatelet only, III: dipyridamole only; IV: none of both were used. Of the four groups, group IV exhibited highest AVF patency (52.4%), which was followed by group III (42.7%), group II (40%), and group I (28.6%), respectively. Compared with group IV, only group I showed a significantly higher risk for AVF patency loss. None of the cardiovascular medications evaluated in the present study showed a beneficial effect on AVF patency. Furthermore, dipyridamole showed an association with a higher risk of AVF patency loss. We do not suggest a beneficial effect of dipyridamole on maintaining AVF patency, particularly in combination with antiplatelet agents.

Outcomes after Percutaneous Angioplasty of Arteriovenous Fistulas and Grafts in African American Patients

Purpose

Arteriovenous fistulas and grafts, necessary for hemodialysis, may develop stenoses due to neointimal hyperplasia, which often require percutaneous transluminal angioplasty. Patient and lesion characteristics were evaluated prior to angioplasty and were correlated with 1- and 6-month outcomes.

Materials and Methods

This was an observational study of African American hemodialysis patients who presented for angioplasty of a dysfunctional fistula or graft. Clinical outcomes were ascertained from dialysis facilities 1 month and 6 months after angioplasty. One-month clinical success was defined as dialyzer blood flows of 450 mL/min without complications or interval shunt thrombosis, interventions, or loss of access, which was rarely achieved at 6 months. Logistic regression models were used to evaluate associations of clinical variables with outcomes.

Results

There were 150 stenoses treated during 99 procedures performed on 82 patients. The clinical success rate at one month was 67% with no complications as a result of the percutaneous transluminal angioplasty. Success at 1 month was positively associated with use of aspirin ( P = .005) and with referral for high venous pressures ( P = .004). Six-month data were available for 81 procedures, with 45.7% requiring repeat angioplasty and 12.3% suffering major complications (thrombectomy, revision surgery, or access abandonment). Major complications were seen predominantly in patients who were not receiving aspirin.

Conclusions

Aspirin use and high venous pressure were associated with 1-month clinical success and fewer major complications at 6 months. Future work should investigate biologic mechanisms of action of aspirin and long-term effects of use to maintain vascular access.

Antiplatelet agents maintain arteriovenous fistula and graft function in patients receiving hemodialysis: A nationwide case-control study

Background

In this study, we evaluated the effects of various medications on the patency of vascular access (VA) for hemodialysis.

Methods

We analyzed data from the Longitudinal Health Insurance Database of Taiwan. We adopted a case–control study design within a cohort of patients who had received regular hemodialysis between 2002 and 2012; 34,354 patients with first VA failure were identified, and the duration from VA creation date to the first VA failure date was calculated. We then classified these patients into two groups, namely arteriovenous fistula (AVF, n = 25,933) and arteriovenous graft (AVG, n = 8,421). Each group was further divided into two subgroups, namely short-term (<1 year) and long-term (≥1 year) patency.

Results

The risk factors for early VA failure were age ≥65 years, diabetes mellitus, hyperlipidemia, cerebral vascular disease, congestive heart failure, peripheral artery disease, and sepsis. Male sex, hypertension, cancer, and peptic ulcer were associated with early AVF failure. Antiplatelet therapy increased the AVF and AVG patency times with adjusted odds ratios of 0.748 (95% confidence interval [CI]: 0.703–0.796, p < 0.0001) and 0.810 (95% CI: 0.728–0.901, p = 0.0001), respectively. A significant decrease in the VA failure risk was observed with an increase in the cumulative defined daily dose of antiplatelet agents.

Conclusion

This nationwide study demonstrated that some risk factors were associated with early VA failure and that the use of antiplatelet agents prevented the loss of VA patency in a dose–response manner. Thus, antiplatelet drugs should be routinely administered to high-risk patients receiving dialysis.

Effects of N-acetylcysteine on arterial neo-intimal hyperplasia in rat model of arteriovenous fistula

INTRODUCTION:

Arteriovenous fistula is the best choice for vascular access in hemodialysis patients. However, arteriovenous fistula dysfunction is a major clinical issue. The most common cause of arteriovenous fistula failure is intimal hyperplasia. In this study, we have investigated the effect of N-acetylcysteine on neo-intimal hyperplasia after arteriovenous fistula creation in rats.

METHODS:

This study was conducted in 24 rats which were randomly divided into two groups: control and N-acetylcysteine groups. An end-to-side anastomosis was made between the femoral artery and vein. The control group received distilled water intraperitoneally while the animals in N-acetylcysteine group received 300 mg/kg/day of N-acetylcysteine via the same route. After 28 days, the thickness of intima and media was measured using hematoxylin and eosin.

RESULTS:

There was no significant difference between the two groups regarding age ( p = 0.6) and weight ( p = 0.1). The mean intima thickness in N-acetylcysteine group was significantly less than control group (17 ± 20 and 119 ± 46 µm, respectively; p < 0.001). The mean intima/media thickness in the N-acetylcysteine group was significantly less than control group (0.5 ± 0.63 vs 2.05 ± 1.17 µm; p < 0.001).

CONCLUSION:

N-acetylcysteine is effective in inhibiting neo-intimal hyperplasia in a rat model of arteriovenous fistula.

Maturation of arteriovenous fistula: Analysis of key factors

The growing proportion of individuals suffering from chronic kidney disease has considerable repercussions for both kidney specialists and primary care. Progressive and permanent renal failure is most frequently treated with hemodialysis. The efficiency of hemodialysis treatment relies on the functional status of vascular access. Determining the type of vascular access has prime significance for maximizing successful maturation of a fistula and avoiding surgical revision. Despite the frequency of arteriovenous fistula procedures, there are no consistent criteria applied before creation of arteriovenous fistulae. Increased prevalence and use of arteriovenous fistulae would result if there were reliable criteria to assess which arteriovenous fistulae are more likely to reach maturity without additional procedures. Published studies assessing the predictive markers of fistula maturation vary to a great extent with regard to definitions, design, study size, patient sample, and clinical factors. As a result, surgeons and specialists must decide which possible risk factors are most likely to occur, as well as which parameters to employ when evaluating the success rate of fistula development in patients awaiting the creation of permanent access. The purpose of this literature review is to discuss the role of patient factors and blood markers in the development of arteriovenous fistulae.

Impact of Statins on Arteriovenous Fistulas Outcomes: A Meta-Analysis

Statins are effective lipid-lowering drugs with beneficial pleiotropic effects for vascular remodeling processes, statins may have a beneficial effect on the function of arteriovenous fistulas (AVFs) in hemodialysis (HD) patients. Therefore, we performed this systematic review to assess the protective effects of statin therapy in HD patients. The randomized controlled trials (RCTs) or quasi-RCTs and retrospective cohort studies (RCS) of statin therapy for the function of AVFs in HD patients were searched from multiple databases. Relevant studies were screened according to predefined inclusion criteria and then pooled-analyses were performed using RevMan 5.2 software. One RCT and six RCS containing 20 246 HD patients were included in this meta-analysis, of whom 9847 were treated with statins and 10 399 were treated with placebo. Our meta-analysis showed that there was no significant difference between statins and placebo groups, with those who received statin therapy showing similar AVF failure rates compared to control (pooled risk ratio = 0.89; 95% CI, 0.70 to 1.12, P = 0.32), and there was obvious evidence of statistical heterogeneity (P = 0.005; I²  = 68%). In addition, subgroup pooled analyses revealed that statin therapy did not ameliorate AVF failure in participants from the same racial background or similar sample size trials. There was no evidence that statins therapy could reduce the AVFs failure. However, due to methodological limitations and obvious statistical heterogeneity, high-quality, long-term and multicenter trials are required to fully elucidate the clinical value of statins administration for the outcomes of AVFs in HD patients.

Efficacy of statin on vascular access patency in diabetic hemodialysis patients

INTRODUCTION

An effective approach to prevent hemodialysis vascular access dysfunction is still unclear despite previous studies, which have shown conflicting results of several drugs on vascular access outcomes. In this study, we focused on diabetic hemodialysis patients with native arteriovenous fistula and evaluated the impact of statin treatment on vascular access patency.

METHODS

A retrospective cohort study of 268 consecutive patients who newly started hemodialysis due to diabetic nephropathy between January 2011 and December 2013 at Japan Community Health Care Organization Sendai Hospital was performed and the patients were followed for two years. The primary outcome was vascular access dysfunction. Effect of statin treatment was examined using Kaplan Meier analysis and Cox proportional hazard, after adjusting for covariates.

RESULTS

The mean follow-up period was 426.7 days, and 117 (52.2%) patients developed vascular access dysfunction. The two-year patency rate was 55.0% among statin users and 36.1% in non-users. Vascular access survival period was significantly longer among statin users (log-rank test, p = 0.004). In multivariable analysis, statin treatment is significantly associated with better vascular access outcomes, in which the hazard ratio was 0.71 (95% CI, 0.52 to 0.97; p = 0.028) in the unadjusted model and 0.63 (95% CI, 0.45 to 0.88; p = 0.007) after adjustment for covariates.

CONCLUSIONS

Statin treatment could be associated with improved vascular access dysfunction among diabetic hemodialysis patients.

Distinct impact of three different statins on arteriovenous fistula outcomes: a retrospective analysis

PURPOSE

Whether statins improve arteriovenous fistula (AVF) outcomes is still a matter of debate. Taking into consideration the existing physicochemical differences between individual drugs, this study evaluates the impact of three different statins (atorvastatin, rosuvastatin and simvastatin) on one-stage and two-stage AVF outcomes.

METHODS

Using a retrospective cohort of 535 patients, we analyzed the effects of each statin on primary failure and primary patency using multivariate logistic regressions and Cox proportional hazard models.

RESULTS

Out of the three statins analyzed, only atorvastatin improved the overall primary failure of AVF (odds ratio [OR] = 0.18, p = 0.005). Comparisons between the two AVF types demonstrated that this effect was due to a prominent reduction in primary failure of one-stage (OR = 0.03; p = 0.005), but not two-stage fistulas (OR = 0.43; p = 0.25). In contrast, primary patency of two-stage (hazards ratio [HR] = 0.51; p = 0.024), but not one-stage fistulas (HR = 0.98; p = 0.95), was improved by all statins as a group, but not by individual drugs.

CONCLUSIONS

Our results suggest that the potential benefit of statins on AVF outcomes is a drug-specific and not a class effect, and that such effect is also influenced by the type of fistula.

Use of a proactive duplex ultrasound protocol for hemodialysis access

OBJECTIVE

Arteriovenous fistula (AVF) creation is the preferred approach for hemodialysis access; however, the maturation of AVFs is known to be poor. We established a proactive early duplex ultrasound (DUS) surveillance protocol for evaluating AVFs before attempted access. This study determined the effect of this protocol related to improving AVF maturation.

METHODS

From 2008 to 2013, 153 patients received new upper extremity AVFs and an early DUS surveillance protocol at a single academic institution. The protocol involved an early DUS evaluation before hemodialysis cannulation of the AVF at 4 to 8 weeks after AVF creation. A positive DUS result was identified as a peak systolic velocity of >375 cm/s or a >50% stenosis on gray scale imaging, along with decreased velocity in the outflow vein. Patients with positive DUS findings underwent prophylactic endovascular or open intervention to assist with AVF maturation. Nature of secondary interventions, as well as AVF patency and maturation, were assessed. Overall clinical outcomes and fistula patency were investigated.

RESULTS

During the study period, 183 upper extremity AVFs were created in 153 patients, including 82 radiocephalic, 63 brachiocephalic, and 38 brachiobasilic AVFs. A mortality rate of 43% (n = 66) was observed in a median follow-up period of 34.5 months (interquartile range, 19.6-46.9). A total of 164 early DUS were performed at a median of 6 weeks (interquartile range, 3.4-9.6 weeks) after the initial creation. Early DUS showed nine AVFs were occluded and were excluded from further analysis. Hemodynamically significant lesions were found in 62 AVFs (40%); however, only 17 (11%) were associated with an abnormal physical examination. Positive DUS finding prompted a secondary intervention in 81% of the patients. Among those with positive early DUS findings, AVF maturation was 70% in those undergoing a secondary intervention compared with 25% in those not undergoing a prophylactic intervention (P = .011). Primary-assisted patency for AVFs with early positive and negative DUS findings were 83% and 96% at 6 months, 64% and 89% at 1 year, and 52% and 82% at 2 years, respectively (P < .001).

CONCLUSIONS

Early DUS surveillance of AVFs before initial access is reasonable to identify problematic AVFs that may not be reliably detected on clinical examination. Although DUS criteria for AVFs have yet to be universally accepted, proactive early postoperative DUS interrogation assists in the early detection of dysfunctional AVFs and improvement of fistula maturation. Despite improved patency in those with positive DUS findings who undergo prophylactic secondary intervention, overall patency remains inferior to those without an abnormality detected on early DUS imaging.

Statins Improve Long Term Patency of Arteriovenous Fistula for Hemodialysis

The protective effects of statins against stenosis for permanent hemodialysis access have been repeatedly demonstrated in animal studies, but remain controversial in human studies. This study aims to evaluate the association between statin use and permanent hemodialysis access patency using a nationwide hemodialysis cohort. A total of 9862 pairs of statin users and non-users, matched by age and gender, were selected for investigation from 75404 new hemodialysis patients during 2000-2008. The effect of statins on permanent hemodialysis access patency was evaluated using Cox proportional hazards models. Compared with non-users, statin users had an overall 18% risk reduction in the composite endpoint in which angioplasty and recreation were combined (adjusted hazard ratio = 0.82 [95%CI, 0.78-0.87]) and 21% in recreation of permanent hemodialysis access (adjusted hazard ratio = 0.79 [95%CI, 0.69-0.80]). Specifically, the protective effect was found for arteriovenous fistula (adjusted hazard ratio = 0.78[95% CI, 0.73-0.82] for composite endpoint and 0.74 [95% CI, 0.69-0.80] for vascular recreation), but not for arteriovenous grafts (adjusted hazard ratio = 1.10 [95% CI, 0.98-1.24] and 0.94 [95% CI, 0.83-1.07]). Statins possess a protective effect for arteriovenous fistula against the recreation of permanent hemodialysis access. The results provide a pharmaco-epidemiologic link between basic research and clinical evidence.

Risk of arteriovenous fistula failure associated with hypnotic use in hemodialysis patients: a nested case-control study

PURPOSE

Hypnotic use might cause altered inflammatory processes, which have been suggested as being related to the mechanisms of arteriovenous fistula (AVF) failure. Therefore, we examined the association between the risk of AVF failure and hypnotic use in patients receiving hemodialysis (HD).

METHODS

A nested case-control study was conducted using data from the National Health Insurance Research Database of Taiwan. From 34 165 HD patients, 3676 patients receiving percutaneous transluminal angioplasty or surgical thrombectomy for AVF failure were matched to 14 704 control patients according to sex, age (±1 year), and the year of initial HD therapy. The risk of AVF failure was estimated based on conditional logistic regression after adjustment for the timing of AVF creation, HD frequency, comorbidities, and prescribed medications. Hypnotic use was measured prior to the date of AVF failure of case patients and the date of pseudo-AVF failure of controls.

RESULTS

Compared with matched controls, case patients were more likely to be exposed to hypnotics 30 days or an average daily defined dose > 0.5 within 90 days before the date of AVF failure, with an adjusted odds ratio of 1.21 (95% confidence interval [CI]: 1.09-1.35, p < 0.001) and 1.36 (95%CI: 1.13-1.63, p = 0.001), respectively. Risk of AVF failure associated with hypnotic use was also observed among HD patients who were male, were younger than 65 years, had hypertension, and did not use statins.

CONCLUSIONS

Hypnotic use among HD patients was associated with an increased risk of AVF failure. Copyright © 2016 John Wiley & Sons, Ltd.

The effect of lowering LDL cholesterol on vascular access patency: post hoc analysis of the Study of Heart and Renal Protection

BACKGROUND AND OBJECTIVES

Reducing LDL cholesterol (LDL-C) with statin-based therapy reduces the risk of major atherosclerotic events among patients with CKD, including dialysis patients, but the effect of lowering LDL-C on vascular access patency is unclear.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Study of Heart and Renal Protection (SHARP) randomized patients with CKD to 20 mg simvastatin plus 10 mg ezetimibe daily versus matching placebo. This study aimed to explore the effects of treatment on vascular access occlusive events, defined as any access revision procedure, access thrombosis, removal of an old dialysis access, or formation of new permanent dialysis access.

RESULTS

Among 2353 SHARP participants who had functioning vascular access at randomization, allocation to simvastatin plus ezetimibe resulted in a 13% proportional reduction in vascular access occlusive events (355 [29.7%] for simvastatin/ezetimibe versus 388 [33.5%] for placebo; risk ratio [RR], 0.87; 95% confidence interval [95% CI], 0.75 to 1.00; P=0.05). There was no evidence that the effects of treatment differed for any of the separate components of this outcome. To test the hypothesis raised by SHARP, comparable analyses were performed using the AURORA (A Study to Evaluate the Use of Rosuvastatin in Subjects on Regular Hemodialysis: An Assessment of Survival and Cardiovascular Events) trial cohort. AURORA did not provide independent confirmation (vascular access occlusive events: 352 [28.9%] for rosuvastatin versus 337 [27.6%] for placebo; RR, 1.06, 95% CI, 0.91 to 1.23; P=0.44). After combining the two trials, the overall effect of reducing LDL-C with a statin-based regimen on vascular access occlusive events was not statistically significant (707 [29.3%] with any LDL-C-lowering therapy versus 725 [30.5%] with placebo; RR, 0.95, 95% CI, 0.85 to 1.05; P=0.29).

CONCLUSIONS

Exploratory analyses from SHARP suggest that lowering LDL-C with statin-based therapy may improve vascular access patency, but there was no evidence of benefit in AURORA. Taken together, the available evidence suggests that any benefits of lowering LDL-C on vascular access patency are likely to be modest.

The effect of statin therapy on the formation of arteriovenous fistula stenoses and the rate of reoccurrence of previously treated stenoses

Statins reduce inflammation in end-stage renal disease patients and improve endothelial function beyond cholesterol lowering. Despite this, statins do not improve the maturation rate, primary patency rate, and the cumulative survival of arteriovenous fistulas (AVFs). It is unknown if statins decrease the number of stenoses developing in AVFs or prolong the intervals between angioplasties needed to treat recurring stenoses. We conducted a retrospective chart review of our 265 active dialysis patients. The statin group was significantly more likely to be diabetic (64% vs. 43.6%) and treated with aspirin (64% vs. 40%) when compared to those not treated with statins (P=0.04 and 0.01). The mean time to first intervention (primary patency) was 16.5 months in statin users and 15.8 months in the nonstatin group (P=0.49) with standard deviations of ± 18.5 and 16.6 months, respectively. Statin use was not associated with a significant decrease in the number of stenoses diagnosed (P=0.28). The mean time between recurrent stenoses' angioplasties was 8.9 months in statin users and 7.3 months in the nonstatin patients (P=0.25). Aspirin users were more likely to have a decreased primary patency (rate ratio=1.65, P=0.03) compared with nonaspirin users. Patients who were prescribed aspirin developed 1.6 (P 0.01) times more stenoses than those not treated with aspirin. We report for the first time that statin therapy does not decrease the number of stenotic lesions developing in the AVF or prolong the interval between procedures required to treat recurrent stenoses.

Statin therapy and hemodialysis vascular access--were we bringing a knife to a gunfight and were hoping to win?

Vascular access dysfunction is a major contributor to end stage renal disease patient morbidity, and the cost of maintaining it is staggering. Any intervention able to improve the vascular access maturation rate and/or patency would be significant progress. Based on the anti-inflammatory and vascular beneficial effects demonstrated in non-end stage renal disease patients, we were hoping that statin use might provide the much needed improvement in the hemodialysis vascular access outcome. The reality proved disappointing. The statins failed to improve every aspect of hemodialysis vascular access studied. The present editorial discusses the current data regarding the effect of statins on vascular access and attempts to explain their lack of success.

Pharmacotherapy to improve outcomes in vascular access surgery: a review of current treatment strategies

BACKGROUND

Renal failure is a major cause of morbidity in western Europe, with rising prevalence. Vascular access complications are the leading cause of morbidity among patients on haemodialysis. Considering the health care burden of vascular access failure, there is limited research dedicated to the topic.

METHODS

Randomised control trials of medications aimed at improving vascular access patency were identified using a medline search between January 1950 and January 2011.

RESULTS

Thirteen randomised trials were identified, investigating antiplatelets, anticoagulants and fish oil in preserving vascular access patency. Outcomes are presented and reviewed in conjunction with the underlying pathophysiological mechanisms of failure of vascular access.

DISCUSSION

Vascular access failure is a complex process. Most clinical trials so far have involved medications primarily aimed at preventing thrombosis. Other contributing pathways such as neointimal hyperplasia have not been investigated clinically. Improved outcomes may be seen by linking future therapies to these pathways.

Statin therapy is not associated with improved vascular access outcomes

BACKGROUND AND OBJECTIVES

Neointimal hyperplasia is the major cause of vascular access failure in hemodialysis patients. Statins reduce neointimal hyperplasia in experimental models, which may reduce access failure. The study presented here evaluated whether vascular access outcomes are superior in patients receiving statin therapy than in those not on statins.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A prospective computerized vascular access database was retrospectively queried to determine the access outcomes of 601 patients receiving an upper-arm fistula or graft at a single large dialysis center.

RESULTS

Primary fistula failure was observed in 37% of patients on statin therapy versus 38% not on statin therapy. Primary graft failure occurred in 20% of patients on statin therapy versus 14% not on statin therapy. A multiple variable logistic regression analysis including statin use, diabetes, coronary artery disease, peripheral artery disease, sex, and age found that only sex predicted primary fistula failure and graft failure. After excluding primary failures, cumulative fistula survival was similar for patients with or without statin therapy (hazard ratio [HR] 1.26; 95% confidence interval [CI] 0.76 to 2.16). Likewise, cumulative graft survival was similar for statin therapy versus no statin therapy (HR 0.88; 95% CI 0.59 to 1.32). Using a multivariable survival analysis model to predict cumulative fistula survival, only age predicted fistula failure (HR 1.21 per decade; 95% CI 1.02 to 1.44). None of the variables in this model predicted cumulative graft survival.

CONCLUSIONS

Statin therapy is not associated with improved fistula or graft outcomes in patients with chronic kidney disease.