The association of long-term blood pressure variability with hemodialysis access thrombosis.

Background: Blood pressure variability (BPV) is an important risk factor for cardiovascular events in hemodialysis patients. We sought to determine the impact of BPV on hemodialysis access thrombosis. Methods: We enrolled 1,011 prevalent hemodialysis patients from 12 hemodialysis centers since January 2018 and followed them until December 2020. Predialysis blood pressure (BP) was assessed at 12-week intervals. The coefficient of variation derived from 36 consecutive BP measurements was used as the metric for variability. The primary outcome was incident hemodialysis access thrombosis. Linear regression models were used to assess factors associated with BPV at baseline. Kaplan-Meier curves of the time until vascular access events were drawn and log-rank tests were calculated. Cox proportional hazards models were performed to assess the association of BPV with incident vascular access events. Results: The average coefficient of variance for systolic BPV was 10.9%. BPV was associated with age, body mass index, mean BP, diabetes, coronary and peripheral artery disease, history of access dysfunction, graft access, intradialytic hypotension, and use of antihypertensive medications. There were 194 access thrombosis events and 451 access stenosis events during a median follow-up period of 30 months. After adjustment of potential confounding factors, BPV was associated with increased risk of access thrombosis [hazard ratio = 1.27, 95% confidence interval (CI), 1.18-1.44, per 1 standard deviation increase in BPV]. The patients in the highest BPV quartile had 2.45 times the risk of thrombosis (CI, 1.62-3.70). The association was independent of average BP, intradialytic hypotension, and comorbidities. Similar trends of association were found in the subgroups analyzed. Comparative analysis using a time-varying variable model and different metrics of BPV showed consistent results. Conclusion: Our findings underscored the impact of BP fluctuation on vascular access thrombosis.

Association of Frailty With Thrombosis of Hemodialysis Vascular Access: A Prospective Taiwanese Cohort Study.

RATIONALE & OBJECTIVE: Frailty, a multidimensional construct, has been associated with poor outcomes in patients receiving maintenance dialysis. This study assessed the association of frailty with dialysis vascular access patency. STUDY DESIGN: Multicenter prospective cohort study. SETTING & PARTICIPANTS: 761 prevalent patients receiving hemodialysis at 9 centers in Taiwan as of January 2018. EXPOSURE: Performance-based frailty was defined as 3 of the following: unintentional weight loss, weakness, exhaustion, low physical activity, and slow gait speed. Patients were categorized as prefrail if they had 1 or 2 of these characteristics. OUTCOME: Rate of and time to dialysis access thrombosis. Data regarding vascular access events were collected for 30 months after enrollment through December 31, 2020. ANALYTICAL APPROACH: Logistic regression analysis was used to estimate the association of clinical characteristics with frailty. Cox proportional hazards regression analysis was used to estimate the association of frailty with vascular access thrombosis adjusted for known clinical risk factors. RESULTS: The patients' mean age was 66 years, 46% were female, 18% had synthetic graft accesses, and 82% arteriovenous fistulas. Overall, 31% were frail, 35% were prefrail, and 34% were not frail. The frailty phenotype was associated with age, female sex, low body mass index, diabetes mellitus, and prior stroke. During a median follow-up of 731 days, 161 patients (21%) had access thrombosis events (not frail, 14%; prefrail, 20%; frail, 30%; P < 0.001). Frail patients had a higher risk of vascular access thrombosis than nonfrail patients (HR, 2.31 [95% CI, 1.55-3.39], P < 0.001). After multivariable adjustment for age and comorbidities, frailty remained significantly associated with access thrombosis for both fistulas and grafts. LIMITATIONS: Limited generalizability and potential residual confounding. CONCLUSIONS: Frailty is associated with an increased risk of vascular access thrombosis. These findings highlight the risks of access failure experienced by frail patients receiving hemodialysis.

The Impact of Frailty on the Outcomes of Hemodialysis Vascular Access.

BACKGROUND: Frailty has been associated with mortality and adverse cardiovascular outcomes in patients with hemodialysis (HD), however the relevance of frailty on the outcomes of HD vascular access remains unclear. METHODS: We enrolled a cohort of patients with prevalent HD between August 2018 and November 2018. The presence of 5 frailty phenotypes was determined at enrollment, using the modified Fried's criteria. Data regarding vascular access events or mortality were linked to prospectively collected data up to 24 months after enrollment. RESULTS: Of the 382 patients screened, 313 were recruited in the final analysis. The participants' mean age was 66 years, and 42.5% were female. Among all participants, 40.3% were determined to be frail and 29.4% pre-frail. The frail phenotype was associated with age, female gender, lower body mass index, unemployment, lower education level, and higher dialysis clearance. During the follow-up period (median, 24 months), 112 patients had vascular access events (non-frail, 27.4%; pre-frail, 35.9%; frail, 46.1%; p = 0.003) and 45 patients experienced thrombosis of the vascular access (non-frail, 4.2%; pre-frail, 9.8%; frail, 18.3%; p = 0.002). Cox regression analysis showed that frail patients had a 2.2-fold higher risk of experiencing vascular access events than non-frail patients [hazard ratio (HR): 2.205, 95% confidence interval (CI): 1.377-3.532, p = 0.001], but the association was not significant (HR: 1.634, 95% CI: 0.938-2.848, p = 0.082) after multivariate adjustment. CONCLUSIONS: The frail phenotype is common in Taiwanese patients who undergo maintenance HD and is associated with adverse outcomes of dialysis vascular access.

A randomized feasibility study of the effect of ascorbic acid on post-angioplasty restenosis of hemodialysis vascular access (NCT03524846).

Restenosis remains a significant problem after angioplasty of hemodialysis vascular access. Both experimental and clinical studies have shown a protective effect of antioxidants against post-angioplasty restenosis. A prospective, randomized, feasibility study was conducted to investigate the effect of ascorbic acid to prevent restenosis. Ninety-three hemodialysis patients were randomized into three groups after angioplasty: placebo (n = 31), 300 mg ascorbic acid (n = 31), and 600 mg ascorbic acid (n = 31), treated intravenously 3 times per week for 3 months. Eighty-nine completed the clinical follow-up, and 81 had angiographic follow-up. In the angiographic follow-up, the mean (stand deviation) late loss of luminal diameter for the placebo, 300 mg, and 600 mg groups were 3.15 (1.68) mm, 2.52 (1.70) mm (P = 0.39 vs. placebo group), and 1.59 (1.67) mm (P = 0.006, vs. placebo group), with corresponding angiographic binary restenosis of 79%, 67% (P = 0.38 vs. placebo group), and 54% (P = 0.08 vs. placebo group). The post-interventional primary patency rates at 3 months were 47%, 55% (P = 0.59 vs. placebo group), and 70% (P = 0.18 vs. placebo group) for placebo, 300 mg, and 600 mg groups. Our results demonstrated that intravenous 600 mg ascorbic acid was a feasible therapy and might attenuate restenosis after angioplasty; however, its effect on post-interventional primary patency was modest.

Temporal distribution and biological determinants of thrombotic events after interventions for dialysis vascular access.

Endovascular therapy is the principal therapy for haemodialysis vascular access dysfunction. Nonetheless, the incidence and determinants of post-intervention thrombotic events are unclear. This prospective cohort study evaluated the incidence and timing of thrombotic events after endovascular therapy and analysed the clinical, angiographic, and biological determinants of thrombosis. Of the 236 patients enrolled, 91 experienced post-intervention thrombotic events within 1 year. The 1-year thrombosis-free patency was 28% for thrombosed accesses, 53% for non-thrombosed grafts, and 78% for non-thrombosed fistulas. Forty-one of the 91 thrombotic events (45%) occurred within 3 months post-intervention. In the univariate analysis, early thrombosis was associated with longer haemodialysis duration (hazard ratio [HR], 1.01; 95% confidence interval [CI], 1.01-1.02), graft access (HR, 7.69; 95% CI, 3.33-20.0), multiple stenoses (HR, 2.69; 95% CI, 1.36-5.37), and high indoxyl sulphate (IS) levels (HR, 1.55; 95% CI, 1.32-1.82). Late thrombosis was associated with diabetes (HR, 1.89; 95% CI, 1.01-3.57), cardiovascular disease (HR, 2.38; 95% CI, 1.27-4.54), and endothelial progenitor cell counts (HR, 0.97; 95% CI, 0.93-0.99). After multivariate adjustment, high IS was the major predisposing factor for early post-intervention thrombosis (HR, 1.41; 95% CI, 1.18-1.69). Our findings suggest that measures to decrease IS could target the most critical period of thrombosis.

Thrombophilia Associated with Early Post-angioplasty Thrombosis of Dialysis Vascular Access.

AIM: Percutaneous transluminal angioplasty (PTA) is widely used as the primary treatment for dialysis vascular access dysfunction. Nonetheless, many patients develop early occlusion after angioplasty. Thus, we investigated the role of thrombophilia in access occlusion within 30 days of angioplasty. MATERIALS AND METHODS: This case-control study included patients who underwent PTA for dialysis vascular access dysfunction. Patients who experienced occlusion within 30 days of angioplasty were included in the case group and those without occlusion for at least 30 days after angioplasty were included in the control group. All patients were tested for protein C, protein S, antithrombin III, lupus anticoagulant, and anticardiolipin antibodies. RESULTS: From February to October 2015, 462 patients underwent PTA for dialysis vascular access dysfunction. Forty-one patients (8.9%) had early occlusion within 30 days of angioplasty. The case group had more graft accesses (73 vs. 31%, P < 0.001) and thrombotic occlusions (67 vs. 15%, P < 0.001). A higher incidence of protein C (10 vs. 2%), protein S (15 vs. 5%), and antithrombin III (10 vs. 2%) deficiency and elevated anticardiolipin antibody (22 vs. 10%) levels were observed in the case group. Overall, 26 patients (63%) in the case group had at least one thrombophilic factor, compared with 15 patients (37%) in the control group (unadjusted odds ratio [OR], 3.004; 95% confidence interval [CI], 1.223-7.380; P = 0.027). After adjustment for confounding factors, the association between thrombophilic factors and early occlusion remained (adjusted OR, 3.806; 95% CI, 1.018-14.220; P = 0.047). CONCLUSION: Thrombophilia is associated with early occlusion after angioplasty for hemodialysis vascular access.