Equal first authors
The patency of arteriovenous access is important for stable and effective hemodialysis, and long-term technical survival is best achieved with a native arteriovenous fistula (AVF). However, maintaining AVF patency remains a challenge. This study was designed to determine the independent prognostic factors for AVF patency according to hemodialysis duration.
The primary study end point was unassisted patency of the AVF, which was defined as the time from the first fistula surgery to the first AVF failure. AVF failure was defined as an event that required percutaneous intervention or surgery to revise or replace the fistula, which occurred at least 2 months after fistula formation.
We enrolled 478 patients with a mean age of 55.5±14.0 years, and mean duration of dialysis was 2.5±2.1 years. There were 109 cases (22.8%) of AVF failure. The factors related to AVF patency differed according to hemodialysis duration. Using a Cox-adjusted model, we observed a significant correlation between the incidence of AVF failure and diabetes within the initial 12 months of hemodialysis. Uncontrolled hyperphosphatemia (mean serum phosphorus>5.5 mg/dL during hemodialysis) was associated with patency loss of AVF after 1 year of hemodialysis.
Various factors were associated with the development of patency loss of AVF as hemodialysis duration differed, and a preventive role of hyperphosphatemia control in AVF survival needs further clinical study.
The survival of arteriovenous fistula (AVF) remains an important problem for hemodialysis patients, accounting for ~20% of all hospitalizations related to AV access problems in western countries. After a continuous effort to increase the placement of autologous AVF in the National Kidney Foundation’s original Dialysis Outcomes Quality Initiative (DOQI), the prevalence of AVF reached up to 55% in March 2010
The clinical risk factors associated with AV access failure are advanced age, diabetes mellitus, poor surgical technique, previous catheter insertion, and history of peripheral vascular diseases
We enrolled end-stage renal disease (ESRD) patients who were treated with maintenance hemodialysis in 2010 at five university or teaching hospitals (Kyung Hee University Hospital, Kyung Hee University Hospital at Gangdong, Konkuk University, Hanyang University Guri Hospital, National Health Insurance Ilsan Hospital) and whose complete medical records were available retrospectively. Patients were included if they met the following criteria: (1) creation of a native AVF as the first vascular access irrespective of temporary catheter use for hemodialysis; (2) formation of the AVF by similar surgical methods with end-to-side anastomosis; and (3) treatment with hemodialysis for 4 h, three times weekly. We excluded patients based on the following criteria: (1) if they received an AV graft with synthetic material as the first vascular access; (2) access failure occurred within the first 2 months after fistula surgery; and (3) if the first episode of AVF failure was related to an infectious complication, steal phenomenon or aneurysm.
Patients’ medical records were used for compiling clinical data retrospectively, including age, gender, underlying causes of ESRD, history of ipsilateral central venous catheter insertion, and the side (right or left) and location (forearm or upper arm) of the AVF. The causes of ESRD were categorized as diabetes mellitus, hypertension, glomerulonephritis, others, or unknown. Laboratory findings, such as serum hemoglobin, serum calcium, phosphate, and intact parathyroid hormone (PTH) were obtained from the medical records. The mean laboratory levels were calculated from the time of the initial AVF occurrence to an AVF event. The primary study end point was unassisted patency of the AVF, which was defined as the time from the first fistula surgery to the first patency loss of AVF. Patency loss of AVF was defined as an event that required percutaneous intervention or surgery to revise or replace the fistula, which occurred at least 2 months after fistula formation. The early event was defined as patency loss of AVF within 1 year of the start of hemodialysis, and the late event was defined as patency loss of AVF after 1 year of hemodialysis. Additionally, patients were censored at the time of kidney transplantation, or if they were transferred to other hospitals, and death with a functioning AVF. The duration between AVF operation and HD initiation can be differed depending on the patient's condition but this difference was not considered in this study.
Continuous variables were expressed as mean±standard deviation. One-way analysis of variance or the Student
A total of 478 hemodialysis patients with ESRD were included in this study.
The patients with patency loss of AVF had a significantly higher prevalence of type 2 diabetes mellitus, mean serum phosphorus level>5.5 mg/dL, and mean calcium×phosphorus product>55 (mg2/dL2,
The unassisted patency of the AVF was significantly lower in diabetic mellitus patients than in nondiabetic patients (
Among the 109 cases of patency loss of AVF, 62 occurred within 1 year of hemodialysis. We explored the risk factors associated with patency loss of AVF before and after 1 year of hemodialysis.
Most risk factors for AVF failure have already been determined at the time of surgery, and there are few studies about risk factors associated with patency loss of AVF according to the duration of hemodialysis. The risk factors during continuous hemodialysis, such as vascular calcification, repeated puncture, and vascular changes in diabetes mellitus may be related to the patency loss of AVF. In this study, we demonstrated that known risk factors of patency loss of AVF were related to early patency loss of AVF. Uncontrolled hyperphosphatemia, however, was related to late patency loss of AVF.
We analyzed clinical risk factors of primary AVF events before and after 1 year. Other recent studies also reported that low intra access blood flow (<500 mL/min), diabetes, older age, and smoking history are clinical risk factors of primary AVF event within 6 months
The Dialysis Outcomes and Practice Patterns Study (DOPPS) showed the difference in fistula placement between Europe and the US
Hyperphosphatemia is closely associated with vascular calcification. Hyperphosphatemia and an elevated Ca×P product are related to cardiovascular mortality in patients with chronic kidney disease
A limitation of this study was that we only evaluated the clinical factors related to AVF survival. Other important factors such as the status of native vein also may influence the patency of AVF.
The present study demonstrated that patency loss of AVF in 478 hemodialysis patients was related to the presence of diabetes and the causative factor within the first year of hemodialysis. Uncontrolled phosphorus level (mean serum phosphorus level>5.5 mg/dL) was the most important factor in AVF failure at 1 year after hemodialysis. The different risk factors were associated with patency loss of AVF according to the hemodialysis duration, and a preventive role of hyperphosphatemia control for AVF survival needs further study.
There is no conflict of interest.
Demographic, vascular access and clinical characteristics of patients (
Age (y) | 55.5±14.0 |
Sex (M:F) | 275:203 |
Mean dialysis duration (y) | 2.5±2.1 |
Cause of ESRD (%) | |
Diabetic nephropathy | 250 (52.3) |
Hypertension | 108 (22.6) |
Glomerulonephritis | 34 (7.1) |
Others | 40 (8.4) |
Unknown | 40 (9.6) |
Comorbidity (%) | |
Diabetes | 263 (55.0) |
Hypertension | 373 (78.0) |
Ischemic heart disease | 92 (19.2) |
Cerebrovascular disease | 48 (10.0) |
Site of AVF (%) | |
Left side | 426 (89.2) |
Right side | 52 (10.8) |
Location of AVF (%) | |
Forearm | 351 (73.4) |
Upper arm | 127 (26.6) |
Temporary catheter use (%) | 183 (38.3) |
Medications (%) | |
Anti-platelet agents | 384 (80.5) |
Warfarin | 11 (2.3) |
Statins | 147 (30.7) |
ACEI or ARB use | 324 (67.7) |
Data are expressed as mean±standard deviation or count (percentage).
ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; AVF, arteriovenous fistula; ESRD, end-stage renal disease.
Clinical characteristics according to patency loss of AVF
Age | 55.5±14.0 | 53.4±14.7 | 0.35 |
Sex (M:F) | 264:174 | 58:54 | 0.07 |
Diabetic nephropathy (%) | 230 (52.6) | 70 (62.5) | 0.04 |
Temporary catheter use (%) | 148 (40.1) | 35 (32.1) | 0.58 |
Site of AVF (%) | |||
Left side | 332 (90) | 96 (88) | |
Right side | 37 (10) | 13 (12) | 0.45 |
Location of AVF (%) | |||
Forearm | 278 (75.3) | 85 (78.0) | 0.08 |
Upper arm | 91 (24.7) | 24 (26.6) | |
Mean serum phosphorus level>5.5 mg/dL (%) | 94 (23.4) | 35 (31.0) | 0.03 |
Mean serum calcium level>9.5 mg/dL (%) | 31 (5.8) | 11 (2.1) | 0.25 |
Mean calcium x phosphorus product>55 mg2/dL2(%) | 31 (5.8) | 15 (2.8) | 0.04 |
Mean iPTH (pg/mL)<150 (%) | 208 (38.8) | 66 (12.3) | 0.26 |
>300 (%) | 52 (9.7) | 12 (2.2) |
Data are expressed as mean±standard deviation or count (percentage).
AVF, arteriovenous fistula; iPTH, intact parathyroid hormone.
Independent factors prognostic of the AVF survival according to the hemodialysis duration
Factor | ||||
---|---|---|---|---|
Hazard ratio | Hazard ratio | |||
Unadjusted Cox model | ||||
Male sex | 1.04 | 0.87 | 0.57 | 0.05 |
Age | 1.01 | 0.46 | 1.01 | 0.83 |
Diabetic mellitus | 2.37 | 0.002 | 1.19 | 0.66 |
Ischemic heart disease | 1.12 | 0.25 | 1.27 | 0.27 |
Mean serum phosphorus level > 5.5 mg/dL | 1.20 | 0.71 | 1.85 | 0.03 |
Mean serum calcium level > 9.5 mg/dL | 1.01 | 0.99 | 1.04 | 0.94 |
Mean serum Ca x P > 55 | 1.10 | 0.83 | 1.63 | 0.33 |
Mean serum iPTH > 300 | 1.04 | 0.84 | 1.21 | 0.21 |
Multivariate adjusted Cox model | ||||
Diabetic mellitus | 2.37 | 0.002 | 1.60 | 0.132 |
Mean serum phosphorus level > 5.5 mg/dL | 1.20 | 0.710 | 2.17 | 0.009 |
Early event: patency loss of arteriovenous fistula occurred within 1 year of hemodialys initiation; Late event: patency loss of arteriovenous fistula occurred after 1 year of hemodialysis initiation.
Adjusted by sex and age. AVF, arteriovenous fistula; Ca × P, calcium × phosphorus product (mg2/dL2); iPTH, intact parathyroid hormone (pg/mL).