Clopidogrel Diminishes Hemodialysis Access Graft Thrombosis

Prevalence and clinical significance of anatomic variant in cephalic arch on preoperative mapping venography

The aim of the current study was to determine the prevalence of anatomic variant in cephalic arch on preoperative mapping venography and evaluate patency rates and predictors of patency in patients with brachiocephalic fistulas. The prevalence of anatomic variant in cephalic arch was retrospectively evaluated in 1004 consecutive patients who underwent bilateral preoperative mapping venography from July 2006 to December 2018 in a single center. The overall prevalence of anatomic variant in cephalic arch was 17.2% (173/1004). For patency analysis, 128 patients with brachiocephalic fistulas were divided into two groups: a standard anatomy (SA) group (n = 97) and a variant anatomy (VA) group (n = 31). There were no significant differences in clinical characteristics between the two groups. The primary patency rate did not differ significantly between the two groups. The secondary patency rate was significantly (p = 0.009) lower in the VA group than in the SA group. Older age (HR 1.03; 95% CI 1.01-1.05; p = 0.007) was a negative predictor of primary patency, and antiplatelet agent (HR 0.53; 95% CI 0.33-0.84; p = 0.007) and large-diameter cephalic vein (HR 0.52; 95% CI 0.31-0.86; p = 0.012) were positive predictors of primary patency. Older age (HR 1.04; 95% CI 1.01-1.07; p = 0.011) and anatomic variant in cephalic arch (HR 2.9; 95% CI 1.19-7.06; p = 0.019) were negative predictors of secondary patency. The current study provides insight into the clinical significance of anatomic variant in cephalic arch. Anatomic variant in cephalic arch should be considered as a potential risk factor for decreased patency of brachiocephalic fistula during preoperative planning.

Medical adjuvant treatment to increase patency of arteriovenous fistulae and grafts

BACKGROUND

People with end-stage renal disease (ESRD) often require either the formation of an arteriovenous fistula (AVF) or an interposition prosthetic arteriovenous graft (AVG) for haemodialysis. These access sites should ideally have a long life and a low rate of complications (e.g. thrombosis, infection, stenosis, aneurysm formation and distal limb ischaemia). Although some of the complications may be unavoidable, any adjuvant technique or medical treatment aimed at decreasing complications would be welcome. This is the fourth update of the review first published in 2003.

OBJECTIVES

To assess the effects of adjuvant drug treatment in people with ESRD on haemodialysis via autologous AVFs or prosthetic interposition AVGs.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and ClinicalTrials.gov trials register to 6 August 2020.

SELECTION CRITERIA

Randomised controlled trials of active drug versus placebo in people with ESRD undergoing haemodialysis via an AVF or prosthetic interposition AVG.

DATA COLLECTION AND ANALYSIS

For this update, two review authors (IM, MFAK) independently selected trials for inclusion, extracted data, assessed risk of bias and assessed the certainty of the evidence according to GRADE. We resolved disagreements by discussion or consultation with another review author (ADS). The primary outcome was the long-term fistula or graft patency rate. Secondary outcomes included duration of hospital stay; complications such as infection, aneurysm formation, stenosis and distal limb ischaemia; and number of related surgical or radiological interventions.

MAIN RESULTS

For this update, one additional study was suitable for inclusion, making a total of 13 trials with 2080 participants. Overall the certainty of the evidence was low or moderate due to short follow-up periods, heterogeneity between trials, small sample sizes, and risk of bias due to incomplete reporting. Medical adjuvant treatments used in the included trials were aspirin, ticlopidine, dipyridamole, dipyridamole plus aspirin, warfarin, fish oil, clopidogrel, sulphinpyrazone and glyceryl trinitrate (GTN) patch.  All included studies reported on graft patency by measuring graft thrombosis. There was insufficient evidence to determine if there was a difference in graft patency in studies comparing aspirin versus placebo (odds ratio (OR) 0.40, 95% confidence interval (CI) 0.07 to 2.25; 3 studies, 175 participants; low-certainty evidence). The meta-analysis for graft patency comparing ticlopidine versus placebo favoured ticlopidine (OR 0.45, 95% CI 0.25 to 0.82; 3 studies, 339 participants; moderate-certainty evidence). There was insufficient evidence to determine if there was a difference in graft patency in studies comparing fish oil versus placebo (OR 0.24, 95% CI 0.03 to 1.95; 2 studies, 220 participants; low-certainty evidence); and studies comparing clopidogrel and placebo (OR 0.40, 95% CI 0.13 to 1.19; 2 studies, 959 participants; moderate-certainty evidence). Similarly, there was insufficient evidence to determine if there was a difference in graft patency comparing the effect of dipyridamole versus placebo (OR 0.46, 95% CI 0.11 to 1.94; 1 study, 42 participants, moderate-certainty evidence) and dipyridamole plus aspirin versus placebo (OR 0.64, CI 0.16 to 2.56; 1 study, 41 participants; moderate-certainty evidence); comparing low-intensity warfarin with placebo (OR 1.76, 95% CI 0.78 to 3.99; 1 study, 107 participants; low-certainty evidence); comparing sulphinpyrazone versus placebo (OR 0.43, 95% CI 0.03 to 5.98; 1 study, 16 participants; low-certainty evidence) and comparing GTN patch and placebo (OR 1.26, 95% CI 0.63 to 2.54; 1 study, 167 participants; moderate-certainty evidence). The single trial evaluating warfarin was terminated early because of major bleeding events in the warfarin group. Only two studies published data on the secondary outcome of related interventions (surgical or radiological); there was insufficient evidence to determine if there was a difference in related interventions between placebo and treatment groups. None of the included studies reported on the duration of hospital stay.  Most studies reported complications ranging from mortality to nausea. However, data on complications were limited and reporting varied between studies.

AUTHORS' CONCLUSIONS

The meta-analyses of three studies for ticlopidine (an antiplatelet treatment), which all used the same dose of treatment but with a short follow-up of only one month, suggest ticlopidine may have a beneficial effect as an adjuvant treatment to increase the patency of AVFs and AVGs in the short term. There was insufficient evidence to determine if there was a difference in graft patency between placebo and other treatments such as aspirin, fish oil, clopidogrel, dipyridamole, dipyridamole plus aspirin, warfarin, sulphinpyrazone and GTN patch. The certainty of the evidence was low to moderate due to short follow-up periods, the small number of studies for each comparison, small sample sizes, heterogeneity between trials and risk of bias due to incomplete reporting. Therefore, it appears reasonable to suggest further prospective studies be undertaken to assess the use of these antiplatelet drugs in renal patients with an AVF or AVG.

Role of antiplatelet therapy in the durability of hemodialysis access

BACKGROUND

Antiplatelet therapy (APT) is often used on anecdotal grounds to improve vascular access patency. The aim of this study was to assess the role of APT in hemodialysis (HD) patients undergoing arteriovenous fistula (AVF) or graft (AVG) placement.

METHODS

All patients in a large HD vascular qualitative initiative database (2011-2017) were included and divided into no antiplatelet therapy (no-APT) vs. any APT [aspirin (ASA) or P2Y12 inhibitors (PI)]. Multivariate [logistic (MLR) and Cox (MCR) regression] analyses were used as appropriate.

RESULTS

A total of 24,847 patients undergoing HD access creation were identified (78% AVF). APT was noted among 49 and 46% of AVG and AVF patients, respectively. In MLR analysis, patients on no-APT vs. APT had a 12-fold increased risk of in-hospital mortality (odds ratio (OR) 11.79, [95% confidence interval 5.30-26.26]) and the risk of developing steal syndrome was higher among patients discharged on APT (OR 1.81, [1.19-2.76]). In patients undergoing AVF, primary patency (PP) was similar between APT and no-APT. However, in patients undergoing AVG, PP rates at 12 months were significantly higher for APT: ASA (47 vs. 41%) and PI (51 vs. 41%) than for no-APT (p = 0.008). At MCR analysis, the loss of PP at 12 months was 13% lower in ASA users (hazard ratio (HR) 0.87, [0.77-0.97], p = 0.02) and 24% lower in PI users (HR 0.76, [0.57-0.99], p = 0.046) compared to no-APT.

CONCLUSION

In a large national database, we showed that antiplatelet therapy was associated with lower in-hospital mortality. Aspirin and P2Y12-inhibitor use among AVG patients demonstrated improved PP rates compared to no antiplatelet therapy. We recommend the use of antiplatelet therapy especially in patients on AVG.

[Exhaustion of vascular capital in patients on hemodialysis: what will be the outcome?]

Despite advances in the treatment of chronic renal failure, vascular access remains the weakest link in renal replacement therapy (RRT) and the leading cause of morbidity in patients on hemodialysis We report the case of a young female patient with chronic renal insufficiency secondary to vascular nephropathy on periodic hemodialysis and whose vascular capital was early exhausted due to iterative thromboses in arteriovenous fistulas and failure in peritoneal dialysis. Protein C deficiency was objectified. The patient underwent tunneled hemodialysis catheter insertion at the level of the right atrium via a right anterolateral thoracotomy with cannulation of the inferior vena cava, with poor functional outcome after three months of use. Since then she has been dialyzed using puncture of the external jugular veins.

Medical adjuvant treatment to increase patency of arteriovenous fistulae and grafts

BACKGROUND

End-stage renal disease (ESRD) patients often require either the formation of an arteriovenous (AV) fistula or an AV interposition prosthetic shunt for haemodialysis. These access sites should ideally have a long life and a low rate of complications (for example thrombosis, infection, stenosis, aneurysm formation and distal limb ischaemia). Although some of the complications may be unavoidable, any adjuvant technique or medical treatment aimed at decreasing complications would be welcome. This is the second update of the review first published in 2004.

OBJECTIVES

To assess the effects of adjuvant drug treatment in ESRD patients on haemodialysis via autologous AV fistulae or prosthetic interposition AV shunts.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched March 2015) and CENTRAL (2015, Issue 2).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of active drug versus placebo in people with ESRD undergoing haemodialysis via an AV fistula or prosthetic interposition AV graft.

DATA COLLECTION AND ANALYSIS

For this update, the two review authors (NCT, ADS) independently assessed trial quality and one review author (NCT) extracted data. Information on adverse events was collected from the trials. The primary outcome was the long-term fistula or graft patency rate. Secondary outcomes included duration of hospital stay, complications and number of related surgical interventions.

MAIN RESULTS

For this update, an additional six studies were deemed suitable for inclusion, making a total of 15 trials with 2230 participants. Overall the quality of the evidence was low due to short follow-up periods, heterogeneity between trials and moderate methodological quality of the studies due to incomplete reporting. Medical adjuvant treatments used in the trials were aspirin, ticlopidine, dipyridamole, dipyridamole plus aspirin, warfarin, fish oil, clopidogrel, sulphinpyrazone, and human type I pancreatic elastase (PRT-201). Where possible, the included studies were pooled into similar medical adjuvant groups for meta-analyses.All included studies reported on graft patency by measuring graft thrombosis. There was insufficient evidence to determine if there was a difference in graft patency in studies comparing aspirin versus placebo (three RCTs, 175 participants) (odds ratio (OR) 0.40, 95% confidence interval (CI) 0.07 to 2.25; P = 0.30). The meta-analysis for graft patency comparing ticlopidine versus placebo (three RCTs, 339 participants) favoured ticlopidine (OR 0.45, 95% CI 0.25 to 0.82; P = 0.009). There was insufficient evidence to determine if there was a difference in graft patency in studies comparing fish oil versus placebo (two RCTs, 220 participants; OR 0.24, 95% CI 0.03 to 1.95; P = 0.18); and studies comparing clopidogrel and placebo (two RCTs, 959 participants; OR 0.40, 95% CI 0.13 to 1.19; P = 0.10). Similarly, there was insufficient evidence to determine if there was a difference in graft patency in three studies (306 participants) comparing PRT-201 versus placebo (OR 0.75, 95% CI 0.42 to 1.32; P = 0.31); in one trial comparing the effect of dipyridamole versus placebo (42 participants; OR 0.46, 95% CI 0.11 to 1.94, P = 0.29) and dipyridamole plus aspirin versus placebo (41 participants; OR 0.64, CI 0.16 to 2.56, P = 0.52); in one trial comparing low-dose warfarin with placebo (107 participants; OR 1.76, 95% CI 0.78 to 3.99, P = 0.17); and one trial (16 participants) comparing sulphinpyrazone versus placebo (OR 0.43, 95% CI 0.03 to 5.98, P = 0.53). The single trial evaluating warfarin was terminated early because of major bleeding events in the warfarin group. Only two studies published data on the secondary outcome of related interventions (surgical or radiological); there was insufficient evidence to determine if there was a difference in related interventions between placebo and treatment groups. No studies reported on the length of hospital stay and data reporting on complications was limited and varied between studies.

AUTHORS' CONCLUSIONS

The meta-analyses of three studies for ticlopidine (an anti-platelet treatment), which all used the same dose of treatment but with a short follow-up of only one month, suggest ticlopidine may have a beneficial effect as an adjuvant treatment to increase the patency of AV fistulae and grafts in the short term. There was insufficient evidence to determine if there was a difference in graft patency between placebo and other treatments such as aspirin, fish oil, clopidogrel, PRT-201, dipyridamole, dipyridamole plus aspirin, warfarin, and sulphinpyrazone. However, the quality of the evidence was low due to short follow-up periods, the small number of studies for each comparison, heterogeneity between trials and moderate methodological quality of the studies due to incomplete reporting. It, therefore, appears reasonable to suggest further prospective studies be undertaken to assess the use of these anti-platelet drugs in renal patients with an arteriovenous fistula or graft.

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.

Use of aspirin associates with longer primary patency of hemodialysis grafts

Extended-release dipyridamole plus low-dose aspirin (ERDP/ASA) prolongs primary unassisted graft patency of newly created hemodialysis arteriovenous grafts, but the individual contributions of each component are unknown. Here, we analyzed whether use of aspirin at baseline associated with primary unassisted graft patency among participants in a randomized trial that compared ERDP/ASA and placebo in newly created grafts. We used Cox proportional hazards regression, adjusting for prespecified baseline comorbidities and covariates. Of all participants, 43% reported use of aspirin at baseline; of these, 82% remained on nonstudy aspirin (i.e., excluding ERDP/ASA) at 1 year. After 1 year of follow-up, the incidence of primary unassisted patency among participants using aspirin at baseline was 30% (95% CI: 24 to 35%) and among those not using aspirin was 23% (95% CI: 18 to 27%). Use of aspirin at baseline associated with a dose-dependent prolongation of primary unassisted graft patency that approached statistical significance (adjusted HR, 0.83; 95% CI: 0.68 to 1.01; P=0.06). Use of aspirin at baseline did not associate with prolongation of cumulative graft patency or participant survival. In conclusion, use of aspirin associates with a trend toward longer primary unassisted patency of newly placed hemodialysis grafts similar to that observed for ERDP/ASA.

Antiplatelet agents for the prevention of arteriovenous fistula and graft thrombosis: a meta analysis

AIMS

The aim of this study was to evaluate the impact of antiplatelet agents on the thrombosis rates of arteriovenous fistulae and grafts used for haemodialysis access.

METHODS

In this meta analysis, a systematic search of the literature was used to identify randomised controlled trials evaluating the effect of antiplatelet agents in graft or fistula thrombosis or bleeding. Two authors identified eligible trials and abstracted data on outcomes and study characteristics. The incidence of thrombosis was the primary outcome of interest and was calculated separately for studies evaluating grafts and those evaluating fistulae. A random-effects model was used for statistical pooling.

RESULTS

Ten trials were included in the analysis, nine of which reported outcomes on graft or fistula thrombosis. Antiplatelet agents reduced the rate of arteriovenous fistulae thrombosis (OR 0.54, 95% CI 0.31-0.94) but not grafts (OR 0.50, 95% CI 0.16-1.53). Both analyses had a moderate degree of statistical heterogeneity, likely because of differences in study design, antiplatelet agent and dose, as well as other possible factors. Review of bleeding events did not reveal a concerning risk of bleeding, but could not be statistically evaluated.

CONCLUSIONS

Antiplatelet agents reduce the rate of arteriovenous fistula thrombosis; however, at this time, research does not support the use of these agents for preventing arteriovenous graft thrombosis.

Medical adjuvant treatment to increase patency of arteriovenous fistulae and grafts

BACKGROUND

End-stage renal disease (ESRD) patients often require either the formation of an arteriovenous (A-V) fistula or an A-V interposition prosthetic shunt for haemodialysis.

OBJECTIVES

To determine the effects of adjuvant drug treatment on the patency of fistulae and grafts in patients with ESRD who are undergoing haemodialysis by assessing the number of thrombotic episodes.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group (PVD) searched their Specialised Register (last searched May 2008) and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 2).

SELECTION CRITERIA

RCTs of active drug versus placebo in patients with ESRD undergoing haemodialysis via an A-V fistula or prosthetic interposition A-V graft.

DATA COLLECTION AND ANALYSIS

For the update, two review authors (ADS, GO) independently assessed trial quality and ADS, XE, and GO extracted data. Information on adverse events was collected from the trials. The outcome measure analysed was the long-term fistula or graft patency rate.

MAIN RESULTS

The overall results of the meta-analysis (three RCTs) comparing aspirin versus placebo favoured treatment with aspirin (odds ratio (OR) 0.42, 95% confidence interval (CI) 0.20 to 0.86; P = 0.02).The overall result of the meta-analysis ( three RCTs) comparing ticlopidine (a platelet aggregation inhibitor) versus placebo favoured active treatment (OR 0.47, 95% CI 0.26 to 0.85; P = 0.01).The overall result from one trial comparing the effect of dipyridamole versus placebo and dipyridamole plus aspirin versus placebo favoured treatment (OR 0.57, 95% CI 0.13 to 2.51; OR 0.77, CI 0.19 to 3.19, respectively).One trial compared fish oil (4 g/daily) versus placebo with 24 participants, follow-up 12 months. The overall result favoured treatment (OR 0.07, 95% CI 0.01 to 0.49).One trial compared low-dose warfarin with placebo, 107 patients were followed for 37 months but the trial was terminated prematurely due to increased bleeding events in the treatment group. The overall result favoured placebo (OR 1.76, 95% CI 0.78 to 3.99).One trial compared sulfinpyrazone versus placebo. Sixteen patients, follow-up three months, and the overall result favoured treatment (OR 0.14, 95% CI 0.01 to 1.99).Finally, one trial compared clopidogrel (75 mg/once daily) with placebo. Twenty-four patients, follow-up over a three-year period until their first episode of thrombosis. The overall result favoured treatment (OR 0.01, 95% CI 0.00 to 0.15).

AUTHORS' CONCLUSIONS

The meta-analysis confirmed the beneficial effect of anti-platelet treatment as an adjuvant used to increase the patency of A-V fistulae and grafts in the short term.