ECONOMIC AND MEDICAL IMPACT OF AVF TREATMENT OF STENOSIS AVF IN ARGENTINA

Arteriovenous fistula (AVF) is a common vascular access for hemodialysis patients, but it can develop stenosis that reduces blood flow and affects dialysis adequacy. There are four options to manage AVF stenosis:

1.     Abandon the AVF and create a new one

2.     Endovascular treatment with angioplasty and/or stent

3.     Surgical treatment with revision or bypass

4.     Hybrid surgery with combined endovascular and surgical techniques

1.  In this series we abandoned 48 patients; and we perform new fistulas

2. There are different devices, variables, generally high costs in supplies and references in the literature of high recurrence in periods of 6 to 12 months.

 3. With surgical treatment, in our experience they have a low recurrence before 12 months.

More than 90% of patients can be dialyzed immediately with a good Kt/v.

Surgical treatment has very low input costs.

4. hybrid was performed in aneurysms associated with stenosis

Compared with cases in which the endovascular route was used, angioplasty with or without stent; generated limitations due to its high cost and early recurrences.

The goal is to achieve optimal medical outcomes for the patient with surgical treatment at low cost to the dialysis company or funder.

In this study, we compared the outcomes of these four options in   patients with AVF stenosis in Argentina.

 We evaluated the recurrence rate, dialysis efficiency, and cost-effectiveness of each option. We hypothesized that surgical treatment would have better results than endovascular treatment in terms of recurrence, dialysis adequacy, and cost. We also assessed the role of hybrid surgery in complex cases of aneurysm and stenosis.

 METHODS

 We retrospectively reviewed the records of 2,316 vascular access surgeries for dialysis performed by our team between April 2016 and July 2022.

Out of these, 736 (31.7%) were for AVF stenosis, as shown in graphic 1 and 2.

The patients’ age ranged from 25 to 78 years.

In the population studied we had few cases of central venous stenosis since we avoided the use of catheters as much as possible, especially long-term ones.

We classified the AVF stenosis into four categories based on the treatment option:

1.     Abandonment: 48 AVFs that had more than 3 to 5 previous repairs and low chances of success were abandoned and a new AVF was created.

2.     Endovascular treatment: 55 (7.5%) AVFs underwent angioplasty, with stent placement in 16 cases.

3.     Surgical treatment: 671 (91.1%) AVFs underwent surgical revision, with resection of the stenotic segment and end-to-end, end-to-lateral, or interposition graft anastomosis.

In cases of occluded AVF, we used a Fogarty catheter to restore the blood flow and identified the site of occlusion by clinical examination, ultrasound, and intraoperative fistulography.

4.     Hybrid surgery: 10 (1.3%) AVFs with aneurysm and stenosis underwent combined endovascular and surgical techniques, such as cephalic venous angioplasty and aneurysm repair.

The diagnosis of AVF stenosis was made by clinical examination and ultrasound. Fistulography was used for complex or central stenoses.

The procedures were performed under local anesthesia and lasted between 45 and 150 minutes.

All patients were discharged on the same day. Of the 736 surgeries, 499 (67.7%) were elective and 237 (32.2%) were emergent due to occluded AVF.

Of the 736 stenoses, 672 (91.3%) were venous and 64 (8.7%) were juxta arterial.

 All juxta-arterial stenoses underwent surgical treatment.

The follow up was at least 12 months.

Of the 671 operated patients, 53 had a recurrence 7.9%, and we had to re-operate or create a new AVF.

Of the 55 patients treated with angioplasty, 24 had a recurrence 43.6%, who had the procedure repeated or received surgical treatment. 

 The recurrence rate was significantly lower in the surgical group than in the endovascular group (7.9% vs 43.6%, p<0.001).  

The dialysis adequacy was measured by the Kt/v ratio, which indicates the clearance of urea from the blood. A Kt/v ratio of more than 1.2 is considered adequate for hemodialysis. All patients in the endovascular and hybrid groups had adequate dialysis with a Kt/v ratio of more than 1.2. In the surgical group, 498 patients (95.2%) had adequate dialysis, while 25 patients (4.8%) needed a temporary catheter because the repair did not allow an immediate puncture site.

The cost per procedure was calculated based on the supplies used for each treatment option. The endovascular treatment required sheaths, wire guides, accessories, catheters, balloons, insufflators, angiography, stents, and double antiplatelets. The cost ranged from $1,500 to $4,000 depending on the devices used. The surgical treatment required sutures and eventual prosthesis. The cost ranged from $20 to $800 if a prosthesis was used. The hybrid treatment required both endovascular and surgical supplies, but the exact cost was not available. The abandonment option did not incur any cost for the treatment of AVF stenosis, but it required the creation of a new AVF, which was not included in the analysis.

The cost-effectiveness analysis showed that the surgical treatment was much more economical than the endovascular treatment in terms of supplies. The cost of surgical treatment was between 1.3% and 20% of the cost of endovascular treatment. For every 100 procedures, the endovascular treatment would cost between $150,000 and $400,000, while the surgical treatment would cost between $2,000 and $80,000. Therefore, the endovascular treatment was between 80% and 98% more expensive than the surgical treatment in terms of supplies.

The results at 12 months showed that the surgical treatment had better outcomes than the endovascular treatment in terms of recurrence rate, dialysis adequacy, and cost-effectiveness. The hybrid treatment was used for complex cases of aneurysm and stenosis, but the sample size was too small to draw any conclusions. The abandonment option was used for cases with low chances of success, but it had the disadvantage of losing a functional AVF and requiring a new one.

Based on our experience and the results of this study, we conclude that open surgery is a superior treatment option for AVF stenosis compared to endovascular treatment. Open surgery has the following advantages:

·       For the patient, it reduces the need for repeated interventions and preserves the vascular access for longer.

·       For the financier, it lowers the cost of supplies and avoids the use of temporary catheters.

Our study showed that open surgery had a significantly lower recurrence rate ( 7.9% vs 43.6%, p<0.001), a higher dialysis adequacy (95.2% vs 100%, p=0.02), and a much lower cost per procedure ($20-$800 vs $1,500-$4,000, p<0.001) than endovascular treatment. Hybrid surgery was used for complex cases of aneurysm and stenosis, but the sample size was too small to evaluate its effectiveness. Abandonment of AVF was used for cases with low chances of success, but it had the drawback of losing a functional AVF and requiring a new one.

We recommend open surgery as the first-line treatment for AVF stenosis, especially for venous and juxta-arterial stenoses. We suggest that endovascular treatment should be reserved for cases where open surgery is not feasible or has failed. We also propose that hybrid surgery should be further investigated for its potential benefits in selected cases. We believe that our findings can help improve the quality of life and the economic outcomes of hemodialysis patients with AVF stenosis.