Selective placement of autogenous arteriovenous fistulae in an over 80-year-old population

Abstract

Introduction:

With improved life expectancy and quality of life, elderly patients constitute a progressively larger fraction of consumers utilising renal replacement therapy (RRT). Although substantial data exist for younger cohorts, minimal evidence exists for outcomes of arteriovenous fistula (AVF) and central catheters (CVC) placed in those patients over 80 years. We examined outcomes of primary AVF placement in this cohort to ascertain durability and benefits of AVF in the over 80-year-old population.

Methods:

Retrospective analysis was undertaken of all autogenous AVFs and CVCs placed in patients aged over 80 years at Gold Coast University Hospital between March 2010 and February 2016. Prospectively collected demographic data, co-morbidities and operative factors were analysed.

Results:

Sixty-five AVF and 12 CVC patients were identified. Mean age at intervention was 83.9 years and 76% of the patients were male. The majority of procedures were autogenous radio-cephalic AVF; median post-operative length of stay was 2 days. Cumulative AVF patient survival at 12 and 24 months was 82% and 72%, respectively. This was significantly better than survival rates of CVC patients, with 12-month survival of 45%. Primary patency at 6, 12 and 24 months was 58%, 39% and 31%. There were 113 follow-up procedures in 41 patients required to maintain patency.

Conclusions:

Although patency rates are inferior and re-intervention rates higher than in younger patients, AVF can be a durable option for RRT in selected elderly patients with improved mortality rates compared with CVC. Age alone should not preclude primary AVF placement.

Keywords

Autogenous Dialysis Elderly Fistula Geriatric

Introduction

As society ages, the elderly represents the fastest growing population segment, with those aged over 80 comprising a larger proportion than ever before (1, 2). This has resulted in a commensurate increase in the number of elderly patients diagnosed with chronic kidney disease (CKD) (3). The proportion of patients aged over 65 years starting dialysis has increased by 57% between 1996 and 2003; while the fastest growing segment of the end stage renal disease (ESRD) population is those aged over 75 years (4).

Current evidence and national guidelines recommend autogenous arterio-venous fistulae (AVF) as the first-choice vascular access option for patients commencing haemodialysis (5, 6). This has not always been espoused for elderly patients however, where poor patency rates, concomitant burden of disease and lower life expectancy has guided against AVF placement or even initiation of renal replacement therapy (7, 8). Improvements in medical care and life expectancy mean that the ‘elderly’ now describes a heterogonous group in terms of medical and functional status. Many elderly patients on RRT demonstrate a life expectancy not dissimilar to that of a younger cohort (9). As such controversy exists about whether precluding patients from AVF placement based solely on age remains appropriate (7, 10, 11). This is especially so when the dire life expectancy of elderly patients dialysing through a central venous catheter (CVC) is noted (12). Although evidence suggests that similar outcomes to younger patients in terms of durability and mortality are possible for an elderly cohort and age itself should not preclude AVF placement as a primary dialysis option, significant heterogeneity in study results exists in the published literature (13).

The evidence base for dialysis access options for the elderly is increasing; however, most published studies have employed an age cut-off of 60, 65 or 70 years (7, 14 -18) as the lower bound for categorising the population as ‘elderly’. It is known that overall health status declines rapidly with increasing age, especially for those on RRT (19). AVF outcomes for this over 65-year-old population therefore most likely do not adequately describe expected outcomes in the more elderly and enlarging cohort of over 80-year olds. In addition, while it is postulated that CVC placement portends poorer outcomes than AVF, limited data comparing the two exist in an over 80 population, clouding dialysis access decisions in the very elderly.

We analysed all patients aged over 80 years who were determined as being fit enough to undergo either AVF or CVC placement to assess patency rates and survival outcomes. The aim of this study was to elucidate the durability of such interventions in this more elderly population and determine if a benefit exists for AVF placement in this selected population.

Methods

A retrospective study was undertaken of all vascular access placed for the purpose of haemodialysis in patients aged over 80 years. All procedures were undertaken by vascular access surgeons at the Gold Coast University Hospital or the co-located Allamanda Private Hospital and were performed between January 2010 and February 2016.

All AVFs and CVCs were placed as first access on patients awaiting initiation of haemodialysis. An autogenous AVF at the wrist was the preferred first treatment option; if this was not possible, an alternate access was employed with autogenous conduit preferred. Patients were selected for AVF based on multidisciplinary team consultation involving the renal, radiology and vascular access surgical teams, as well as discussion with the patient. Expected duration of dialysis, life expectancy, quality of life and operative fitness were factors contemplated to determine those most likely to benefit from AVF placement. Criteria employed included perceived cognitive state, modified Eastern Cooperative Oncology Group (ECOG) status (20), co-morbidities and fitness for anaesthesia. Further, clinician perception of likelihood of survival, a robust method of determining expected duration of long-term dialysis (8, 21), played an important role in designating patients likely to survive long enough to benefit from AVF placement. Patients with diminished performance status (ECOG less than 3, multiple co-morbidities, minimal cognitive state, likely to die in the next 12 months) or those with bilateral poor access vessels (veins smaller than 2.5 mm) were either managed with haemodialysis through a CVC or conservatively. Patients were more likely to receive placement of a CVC if they were of good performance status with poor veins or were strongly in favour of starting dialysis. There were 10-15 patients a year who were adjudged as not being fit for dialysis as per the above criteria and managed conservatively. Patients undergoing conservative management were not included in the long-term outcomes of this study.

A prospectively collected database (Excel, Microsoft, Seattle, USA) was employed to record all vascular access procedures between 2010 and 2016; this was used to search the individual cases included in this cohort. Patient demographics including co-morbidities, sex and age were obtained from medical records and recorded. Co-morbidities included ischaemic heart disease (IHD), diabetes, hypertension, smoking and peripheral vascular disease. Operative factors and peri-operative outcomes such as type of anaesthesia, location of fistula, length of stay, early reoperation and early mortality were identified and recorded. Further elective interventions or salvage procedures (either angioplasty or surgical revision) undertaken by vascular access surgery or interventional radiology departments were also recorded.

Patients were followed up until death or the end of the study period. Outcomes recorded were fistula patency, re-interventions, duration of haemodialysis and time and manner of death if applicable were determined via chart review.

Patency rates were defined following the protocols as laid out by North American Vascular Access Consortium (NAVAC) criteria (22). Primary patency was defined as the time from access creation until first intervention to maintain or restore blood flow. Secondary patency was defined as the time from creation until abandonment or death. Primary failure was defined as an AVF that had failed to mature to allow functional dialysis. Functional dialysis was defined as dialysis solely through the fistula for greater than two weeks.

Data were collected and analysed by the authors using SPSS 16 statistical software (IBM, New York, USA). Analysis was undertaken using descriptive statistics. Fistula patency and survival statistics were calculated with Kaplan-Meier survival curves and log-rank test. Fisher’s exact and Mann-Whitney U tests were employed for interrogating demographic data.

Results

Throughout the study period, 65 patients underwent AVF placement and 12 underwent primary CVC placement; demographics and comorbidities are documented in Table I.

Table I

Demographic data of arteriovenous fistula (AVF) and central venous catheter (CVC) patients

Total number	AVF - 65	CVC - 12	p value
Mean age	83.9	87.8	0.07 (NS)^a
Range	80-93	82-92
Male	51 (79%)	10 (83%)	1.00 (NS)^b
Smoking	28 (43%)	4 (33%)	0.75 (NS)^b
IHD	45 (69%)	9 (75%)	1.00 (NS)^b
Hypertension	52 (80%)	11 (92%)	0.68 (NS)^b
Diabetes	20 (31%)	6 (50%)	0.21 (NS)^b

Mann-Whitney U test.

Fisher’s exact test.

IHD = ischaemic heart disease; NS = non-significant; S = significant.

The mean age of patients at placement of initial AVF was 83.9 ± 2.9 years (range 80.1-92.2 years) and 76% of patients were male. While there were high levels of IHD and hypertension in the studied cohort, a relatively low percentage (30%) of patients were diabetic.

The majority of AVFs were radio-cephalic (74%) or brachio-cephalic (20%), the remainder being brachio-basilic or brachio-brachial. Local anaesthetic was used in most cases (92%). Median length of stay was 2 days with a range of 0-70 days. Only one patient required re-intervention on the same admission, for control of peri-operative haemorrhage. No patient died during admission.

Mean follow-up for the AVF group was 1022 ± 684 days and the range was 14 to 2677. Twenty-three patients died over the course of the follow-up period at mean of 572 ± 444 days with a range of 14 to 1474 days. Causes of death are listed in Table II. The most common cause of death was ESRD after cessation of dialysis. The decision to cease dialysis was made by the treating renal physician and the patient or guardians. Decision for cessation was based on factors including new or worsening co-morbid state, functional decline and quality-of-life parameters. Twelve-month survival via Kaplan-Meier analysis was 82%; decreasing to 63% by 3 years (Fig. 1).

Table II

Causes of death over duration of study

Total number	AVF - 23	CVC - 11
Ceased dialysis	8	1
CVA	1	1
IHD	3	2
PermCath sepsis	1	4
Pneumonia/UTI	6	2
Fall	1	0
Neoplastic	3	1

AVF = arteriovenous fistula; CVC = central venous catheter; CVA = cerebrovascular accident; IHD = ischaemic heart disease; UTI = urinary tract infection.

Fig. 1

Kaplan-Meier survival curve for mortality post-procedure. AVF = arteriovenous fistula; CVC = central venous catheter.

Primary patency and secondary patency rates are demonstrated in Figure 2. Primary patency was 58% at 6 months, 39% at 12 months and 31% at 24 months. Secondary patency was 100% at 6 months and 93% at 24 months, respectively. Primary failure rate was 16%. For maintenance of patency, 113 follow-up interventions in 41 patients were performed; the majority of these being endovascular (Tab. III).

Fig. 2

Kaplan-Meier survival curve for arteriovenous fistula (AVF) patency rate post-procedure.

Table III

Method of re-intervention for maintenance of patency

Total number	113
Percutaneous fistuloplasty	98
Stent	10
Thrombectomy/revision	5

Those commenced primarily on a CVC trended towards being older, 87.8 years, and exhibiting a higher burden of comorbidity (Tab. I); however, these trends were not significant. All patients started on central venous access, apart from one who was lost to follow-up, died over the course of the follow-up period. Mean duration from CVC placement until death was 244 days, with the longest duration of survival being 17 months. Most deaths were from line sepsis and IHD (Tab. II). Kaplan-Meier estimates demonstrated a 12-month survival of 45% (Fig. 1). Mortality was significantly increased for those started on CVC compared to AVF when evaluated with log-rank analysis (p<0.001).

Discussion

This study demonstrates that primary placement of an AVF for haemodialysis can be a durable option in selected patients aged over 80 years and confer improved survival rates than those started on CVC. AVFs are recognised as the gold standard for vascular access in patients requiring RRT (6, 23). Current evidence and national guidelines promote a ‘Fistula First’ strategy to improve infection rates, increase survival, reduce costs and maximise durability compared with other RRT methods (23 -26).

This study suggests that in elderly patients with a good expected quality of life and prognosis, AVF is an effective dialysis method. The elderly forms an increasingly larger proportion of RRT consumers and there is a cohort within this large population group that are living longer and with an increased quality of life. As such, the difficult decisions regarding vascular access options in the elderly will increase in both nuance and frequency. Few studies have examined this intervention on a patient cohort such as elderly as the one described in this study.

Most evidence pertaining to fistula outcomes is derived from an undifferentiated population with primarily a younger mean age. Recent evidence for outcomes of primary fistula placement in populations not stratified by age demonstrates disparate results. A 2014 meta-analysis of 46 articles capturing 7393 fistulas reported a one-year primary patency of 60% and 51% at two years. Secondary patency was found to be 71% at one year and 64% at two years (27). There was wide heterogeneity between results reported from the different studies and a trend towards poorer results in more recently published studies. This may be due to more AVFs placed in poorer operative candidates as management has moved towards a ‘Fistula First’ methodology. Further, this finding may indicate a greater tendency to early intervention in moderately compromised fistulas as comfort with endovascular re-intervention has developed or a purposeful sequential approach to place an AVF with sub-optimal vein before using balloon angioplasty for further maturation.

There have been four previously published studies investigating fistulas placed in those aged over 80 years of age (11, 28 -30), with relatively low numbers in all. In these studies, primary patency at one year ranged from 27%-54% with secondary patency ranging from 38%-93%. These results correlate closely to those presented in this study. Comparing these results to the large volume of meta-analyses of AVF outcomes in the general population, our study reaffirms that primary patency in the over-80 population is substantially poorer. This likely reflects the prevalence of risk factors for reduced fistula patency such as significantly diseased vessels and increased comorbidity burden. The high levels of secondary patency seen in our cohort were mirrored in previous studies, demonstrating that, with close fistula surveillance and prompt intervention, decent medium-term functionality can be obtained.

In our practice, the vascular access liaison team maintain fistula surveillance. Initial follow-up takes the form of clinical and duplex ultrasound assessment 4 weeks’ post-fistula placement and before dialysis has occurred. If problems are encountered at that stage, referral for consideration of intervention is initiated. Once dialysis has commenced, surveillance is undertaken via monthly access-flow studies utilising Transonic Haemodialysis Monitoring (Transonic, New York, USA). Intervention is considered when flows are less than 400 mL/min or there has been a greater than 25% drop in flows in 4 months as per established guidelines (31). If clinical issues with dialysis are encountered, such as inadequate or difficult needling or high pressures, referral is also considered. Once a threatened AVF has been defined, angiography and intervention is undertaken within a two-week period. Such a scheme depends on good multidisciplinary communication and ease of access to quality angiographic intervention.

Confirming previously described results, patients in our study initiating dialysis on CVCs as primary access fared worse than AVF patients. Mean survival post-intervention was 240 days, compared with over 400 for those with AVF and all patients died within the follow-up period. This likely describes the interplay of two competing factors. Firstly, by virtue of patient selection, there was not equivalence between the two groups examined in this study. The AVF group trended towards being younger and less co-morbid than the CVC group, highlighting the inherent selection bias of those determining access options. This predisposes the subset of patients started on CVCs towards poorer long-term results and it is likely that, regardless of which mode of intervention initiated, they would have fared worse than those patients started on AVF. Further, central catheters are known to be an inherently inferior form of dialysis access, exposing the patient to line sepsis access vessel pathology and death (32, 33). This tendency toward increased complication burden with CVCs may exacerbate pathological processes in this already unfit segment of patients, further worsening outcomes. This interaction, that sicker patients get CVCs and CVCs make patients sicker, makes it difficult to fully elucidate what role CVC placement, as opposed to simply poorer patient health to begin with, plays in worsening survival prognosis. However, in spite of this fact, this study indicates that there is a segment of the elderly population better served via AVF placement than CVC placement when commencing dialysis.

Historically, mean life expectancy for over 80-year olds referred for RRT has been lower than in an age-matched cohort (34), with an expected survival of 12-24 months (9, 12, 34, 35); however, it can be as low as 52 days in those in those whom dialysis is started immediately before discharge to nursing home (12). These rates are significantly lower than those described in our study, where AVF candidates were selected as those with a good expected prognosis. By placing AVFs only in this proscribed subset of the ESRD patients, a far more robust cohort was selected, leading to consequently improved life expectancy results. Certainly, the results were superior to those patients managed with CVC placement. It must be noted however that the majority of over 80-year-old patients with ESRD assessed over the course of the study period, 10-15 patients per year, were adjudged as not being fit for dialysis and were managed conservatively. This adds up to significantly more patients not being offered AVF, demonstrating the selective nature of the outcomes in this study. It must be emphasised therefore that the outcomes of this study cannot be extrapolated to the over 80 population as a whole. However, these results do suggest two important points: that vascular access surgeons and renal medicine physicians can adequately identify those RRT patients with better-than-average life expectancy and that those patients, once identified, are potentially better served with a fistula than placement of a central venous catheter or conservative care.

The main limitation of this study is the relatively low sample size, limiting proper interrogation of the factors affecting patency and longevity. The tendency for our department to place a radio-cephalic fistula at the wrist meant that this access method formed most our interventions. Comparison between different forms of AVF was not practical and may indeed be a beneficial avenue of further study. A further weakness of this study was the inability to follow-up those patients who were managed conservatively to fully elucidate outcomes for this cohort and compare them to those patients who did undergo either CVC or AVF placement. More research is required to answer this question.

This study has demonstrated that AVF can be placed safely in a carefully selected elderly population with short length of stay and few complications. Although patency rates are inferior and re-intervention rates are higher than in younger patients, AVF remains a durable and appropriate option for renal replacement therapy in selected elderly patients. AVF placement confers significant survival outcomes compared with CVC placement in selected over 80-year-old ESRD patients. Age alone should not preclude primary AVF placement.

Footnotes

Disclosures

Financial support: No grants or funding have been received for this study.

Conflict of interest: None of the authors has financial interest related to this study to disclose.

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