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| Journal of Vascular Access 2002; 3: 164 - 168 |
| Hemodialysis vascular access among chronic renal failure patients in Egypt |
A. Afifi1, H. Refaat1, A.M. Wahba2, M.A. Karim3, M. El Sharkawy1, A. Ramadan1, A. Aziz1, R. Fayez1
1Department of Internal Medicine and Nephrology, Ain Shams University, Cairo - Egypt
2Department of Vascular Surgery Ain Shams University, Cairo - Egypt
3Department of Community and Public Health, Ain Shams University, Cairo - Egypt
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Search Medline for articles by:
 A. Afifi
H. Refaat
A.M. Wahba
M.A. Karim
M. El Sharkawy
A. Ramadan
A. Aziz
R. Fayez
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ABSTRACT
Background: Proper choice of the vascular access plays a crucial role in dialysis outcome. The prevalence and types of vascular access have not yet been investigated in Egypt. Our work aims to study prevalence, patency rate, complications and factors affecting different types of vascular access in Egypt.
Patients and methods: We studied one thousand hemodialysis patients in eighteen dialysis centers in Egypt.
Results: 93% of the patients had natural arteriovenous access while 7% had synthetic arteriovenous grafts. The patency rate of natural fistulae was significantly higher than that of synthetic grafts (3.07 ± 3 versus 1.5 ± 2 years respectively). Many arteriovenous grafts were done because natural arteriovenous fistula was unsuitable or after its failure. Natural radiocephalic fistula was the most prevalent type (67.3%), with a patency rate significantly higher than all other sites (3.3 ± 3 years). Only 10.2% of patients had a fistula created before the start of dialysis. Thrombosis rate was significantly higher in synthetic arteriovenous grafts (32.4%) than in natural arteriovenous fistulae (9.3%). Diabetes and hyperlipidemia significantly decreased the patency rate of natural arteriovenous fistula but not that of synthetic grafts. Patency of arteriovenous fistula in non-diabetics was 3.2 ± 3.1 years versus 2 ± 1.9 years in diabetics. Patency of arteriovenous fistula in non-hyperlipidemic patients was 3.1 ± 3 years versus 1.5 ± 1.6 years with hyperlipidemia. Temporary vascular access prior to permanent access was used in 90% of patients, of which femoral catheters were used in 53.6%, jugular catheters in 38% and subclavian catheters in 8.4%. The incidence of primary access failure was significantly higher in patients with a previous subclavian catheter insertion.
Conclusions: Natural arteriovenous fistula is the access of choice for hemodialysis patients in Egypt. It has higher patency rate, lower complication rate and nephrologists prefer it. Diabetes and hyperlipidemia decrease patency rate of natural arteriovenous fistula but not synthetic grafts. Subclavian catheter is better avoided due to increased incidence of primary access failure. (The Journal of Vascular Access 2002; 3: 164-8)
Key Words. Hemodialysis, Vascular access, Arteriovenous fistula, Synthetic graft
INTRODUCTION
There are many ways to create vascular access for hemodialysis patients such as temporary catheters (femoral, subclavian and jugular), permanent catheters (jugular), Scribner’s shunts as well as arteriovenous fistulae and grafts (1). An ideal permanent access is able to deliver an adequate flow for the dialysis prescription, is long lasting, and has low complication rates. The autologous AV fistula comes closest to satisfying these criteria because it has the best 5 year patency rate and requires much fewer interventions than other access methods (2). Guidelines developed by the National Kidney Foundation Dialysis Outcomes Quality Initiative promote the use of AV fistulas and earlier referral of patients to nephrologists, permitting early access evaluation and early creation of an AV fistula or graft, thereby minimizing the use of venous catheter access. A second goal of the guidelines is to promote detection of access dysfunction prior to access thrombosis (3). Dispite autologous AV fistula access being clearly the best choice for patients initiating hemodialysis, there is wide use of grafts in the United States (58% use AV grafts while 24% use AV fistulae). In contrast, in Europe AV fistulae are more used than grafts (81% AV fistulae vs 10% grafts) (4). The prevalence and types of vascular access have not as yet been studied in Egypt where 26000 ESRD patients are receiving treatment according to the ministry of health records (99.3% hemodialysis and only 0.7% peritoneal dialysis). Our work aimed to study prevalence, patency, complications and factors affecting different types of vascular access in Egypt.
Patients and methods
Patients
This retrospective cross-sectional study was conducted on 1000 chronic renal failure patients undergoing regular hemodialysis in 18 dialysis centers in Egypt.
Methods
All patients were given a special questionnaire designed to investigate vascular access type, site, patency rate and complications of the vascular access such as thrombosis, inflammation, steal syndrome and pseudoaneurysmal formation. Co-morbid conditions that could affect the access, like diabetes mellitus, hypertension, hypotension, hyperlipidemia, heart failure, anginal attacks and infarction, hypercoagulability, peripheral vascular disease and stroke were considered. Special emphasis was laid upon previous temporary catheters placement and previous permanent access.
Statistical analysis
Statistical analysis of the different variants was done using three tests (Mann-Whitney test, Kruskal-Wallis test and Chi-Square test).
RESULTS
The study included 604 (60.4%) males and 396 females (39.6%). Their age ranged between 10 and 80 years, with a mean value of 47.03 ± 15 years; 929 patients had arteriovenous fistulae (92.9%), while 71 patients had arteriovenous graft (7.1%). Neither patient’s age nor gender affected the patency rates in the two types of arteriovenous access. Patency rate of arteriovenous fistula was 3.07 years ± 3 and patency of arteriovenous graft was 1.5 years ± 2. This difference in patency rate was highly significant (p-value <0.001).
Radiocephalic arteriovenous fistula was the most prevalent type (67.3%), with a patency rate significantly higher than all other sites (3.3 ± 3 years) (Tab. I).
The number of failures of previous arteriovenous fistula among the 1000 patients was 568 operations of which 35.9% were primary failure and 64.% were secondary failure.
Only 10.2 % of the patients had a fistula created before the start of dialysis.
Previous temporary access: the total number of temporary catheters used was 1326. Femoral catheters were used in more than half of patients. The incidence of primary access failure was significantly higher in patients with previous subclavian catheter insertion rather than jugular or femoral catheters (Tab. II).
Thrombosis was more frequent in patients with grafts (32.4%) than in patients with fistula (9.3%). The difference in patency rate was very significantly in favor of AVF. We found no statistically significant difference in the rate of infection, pseudoaneurysm or steal phenomenon between natural and synthetic grafts (p> 0.05). There was increased incidence of difficult vascular connection (28.7%), recurrent hematomas (12.6%), prolonged closure after vascular disconnection (25.6%) in patients with arteriovenous grafts more than in patients with arteriovenous fistulae; 22.1%, 6.7%, 12.2% respectively.
Both diabetes and hyperlipidemia significantly decreased the patency rate of arteriovenous fistula. Diabetes decreased the patency rate of arteriovenous fistula (2 ± 1.9 years versus 3.2 ± 3.1 years in non-diabetic patients. Hyperlipidemia was associated with decreased patency rate of arteriovenous fistula, 1.5 ± 1.6 years versus 3.10 ± 3 years for non-hyperlipidemic patients. Other co-morbid conditions such as hypertension, hypotension, ischemic heart disease, peripheral vascular disease, stroke and heart failure had no significant effect on patency rate of either types.
DISCUSSION
The type of hemodialysis vascular access (fistula, graft or catheter) plays an important role in dialysis outcome. To our knowledge, the prevalence and types of vascular access have not been studied in Egypt. Our work was conducted on one thousand hemodialysis patients in 18 hemodialysis centers. It aimed to study prevalence, patency, complications and factors affecting different types of vascular access in Egypt.
We found that 92.9% of the patients had arterio-
venous fistula; with a mean patency rate of 3.07 ± 3 years and 7.1% of the patients had arteriovenous grafts, with a mean patency rate of 1.5 ± 2 years. Other studies particularly in Europe showed a similar pattern (5-8). In contrast, the use of the arteriovenous fistula has been declining in the United States (9-11). Placement of arteriovenous fistulae exceeds 70-81% in Europe, and 90% in Japan but only 21% in the United States (12, 13). In our study, although the difference between survival of the arteriovenous fistula and the arteriovenous graft was significantly in favor of arteriovenous fistula, it is noteworthy that many of the arteriovenous grafts were done because arteriovenous fistula was unsuitable or failed, so it is unfair to compare the results of both techniques as they were not offered as a primary choice to the patients.
In our study, the radiocephalic fistula was the most prevalent type (67.3%) with a mean patency rate of 3.3 ± 3 years, followed by the ulnobasilic fistula with a mean patency rate of 2.4 ± 2.94, elbow brachiocephalic arteriovenous fistula with a mean patency rate of 2.4 ± 2.61. One survey in the United States showed that the access preferred by nephrologists was the arteriovenous fistula in the lower arm, and a higher risk of access failure in upper arm access versus forearm access (14). Another study showed best results for arteriovenous elbow fistulas in comparison with forearm fistula especially in elderly (15). Radiocephalic fistula remains the preferred access when possible (12).
Only 102 patients had a fistula created before starting dialysis (10.2%). Similar findings were reported in other countries where the majority of patients did not have permanent access at the start of dialysis (16).
We found that females were more likely to receive AVG than males. Similar findings are stated by many authors (10, 17, 18-22).
We found no correlation between age of the patient and survival of the vascular access. Although several studies reached the same conclusion (14, 22, 23), others found that advanced age is a primary risk factor for access thrombosis (13, 24).
In our study, thrombosis was found to be more prevalent in arteriovenous grafts than in arteriovenous access. Several studies strongly agree with our results (13, 25, 26).
We found that diabetes decreased the patency rate of arteriovenous fistula. While some studies revealed similar results (5, 27), others found no significance between access failure and presence of diabetes mellitus (12, 14). Platelet aggregation may be abnormal in patients with diabetes, owing in part to elevated levels of Von Willebrand factor, which predispose to vascular disease and thrombosis (26).
Hyperlipidemia was associated with decreased patency rate of arteriovenous fistula. It is documented that high level of serum lipoprotein(a) is a primary risk factor in the etiology of vascular access thrombosis (24, 28, 29).
Prior subclavian catheter insertion was found to increase the incidence of primary access failure significantly (33% of total failure rate). It is well documented that subclavian vein catheterization may lead to subclavian vein stenosis (26, 30, 31). In our study, the femoral vein catheter was the most likely to be used, followed by jugular catheter, and the least was subclavian catheter. In Italy, temporary jugular access is used in 36% of patients, subclavian in 32% and femoral in 32%. It is clear that despite the documented incidence of related episodes of stenosis/obstruction, the subclavian vein is still used as a temporary access in quite a high percentage of cases worldwide (32).
In conclusion, arteriovenous radiocephalic fistula is the preferred procedure for patients requiring vascular access for hemodialysis due to its longer patency rate and lower rate of complications. Arteriovenous brachiocephalic fistula is the second choice of access construction. Many of the arterio-venous grafts were done as a consequence of arteriovenous fistula being unsuitable or its failure. Diabetes and hyperlipidemia decrease patency rate of arteriovenous fistula but not synthetic grafts. It is better to avoid subclavian catheters due to increased incidence of primary access failure.
ACKNOWLEDGEMENTS
This work has been endorsed by the National Kidney Foundation-Egypt. All the work was on voluntary basis and no payment was received by any of the contributors.
Reprint requests to:
Adel Afifi, MD
6 Labib El Shahed Street
Heliopolis, 11351
Cairo, Egypt
e-mail: aafifi@idsc.net.eg
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