JVA ISSN 1129-7298
J Vasc Access 2015; 00 (00): 000-000 DOI: 10.5301/jva.5000401
ORIGINAL ARTICLE
A prospective observational study to assess the impact of operator seniority on outcome following arteriovenous fistula formation Rachel Barnes, George E. Smith, Ian C. Chetter Academic Department of Vascular Surgery, Hull & East Yorkshire NHS Trust/Hull York Medical School, Hull - UK
Abstract Purpose: Arteriovenous fistula (AVF) surgery affords an excellent opportunity for junior surgeons to learn key vascular techniques. However, implementation of the European Working Time Directive has reduced trainee surgeon’s working hours, leading to concerns regarding a possible effect on patient outcomes. Given high early postoperative failure rates and limited AVF sites, it has been proposed that AVF surgery should be performed by Consultants and senior trainees only. This prospective observational study aimed to establish how seniority impacts upon AVF surgery outcomes. Methods: All patients referred for AVF formation were considered for inclusion. Demographic data, comorbidities, medications and previous access history were recorded. Surgery was performed by a Consultant Vascular Surgeon or a junior surgeon. Clinical review was undertaken 30 days postoperatively to assess patency and record any complications. Results: Seventy-seven patients underwent AVF formation. About 63.6% procedures were carried out by a junior surgeon. The groups were well matched for demographics, comorbidities and medications. There was no difference in anatomical site of formation between groups operated on by consultant versus juniors (p = 0.373). More general anaesthetic procedures were undertaken by Consultant surgeons, for example basilic vein transposition when compared with juniors (p = 0.039). There was no significant difference in terms of early AVF failure (p = 0.710), complication rates (p = 0.139) or requirement for re-intervention (p = 0.256) between the groups. Patency rates were also equivocal between the groups. Conclusions: The seniority of the operating surgeon does not appear to impact on outcomes following AVF formation. A greater proportion of general anaesthetic cases were undertaken by a Consultant, which may introduce bias. Junior surgeons with appropriate training and modest experience can perform access surgery without detriment to patients patient detriment. Keywords: Dialysis, Fistula, Outcomes, Training
Introduction The use of autologous arteriovenous fistulae (AVFs) for the purpose of haemodialysis was first described in 1966 by Brescia et al (1). The AVF is now recognised as the gold standard for maintenance haemodialysis. It has been shown that upper limb AVF has superior long-term patency, reduced Accepted: March 28, 2015 Published online: Corresponding author: Miss Rachel Barnes Academic Vascular Surgical Unit Hull Royal Infirmary Anlaby Road Hull HU3 2JZ, UK
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© 2015 Wichtig Publishing
rates of complications and as such less cost to maintain than grafts or central lines (2). Early referral to access services improves the number of patients commencing dialysis with an AVF, AVF survival, and avoids potential complications related to central venous catheter placement (3). In a cross-sectional study of 750 AVFs and grafts (4), access placed prior to commencing dialysis had a lower failure to mature rate and higher patency rate than those placed once the patient had begun regular dialysis. Early failure is defined as fistulae that never function or fistulae with loss of patency within the first 3 months of their initial use (5). It has been demonstrated that between 15% (6) and 60% (7) of autologous AVF may fail in the early postoperative period. The most frequent cause of failure is venous thrombosis. Some AVFs fail to mature whereby patency is maintained, but the fistula never develops sufficiently to support dialysis.
Arteriovenous fistula formation
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AVF formation is an excellent procedure for vascular surgeons in training to learn the necessary skills and techniques for their specialty. However, the implementation of the European Working Time Directive (EWTD) has significantly reduced the number of hours worked during surgical training with a direct impact on the number of procedures observed and performed by junior surgeons (8). As such, concerns have been raised that this will have a knock-on effect on patient outcomes (9). The evidence regarding the impact of surgeon seniority and level of supervision on outcomes following vascular and general surgical procedures is limited and often contradictory. Outcomes following index vascular procedures were shown to be similar when carried out by trainees as opposed to Consultants; however, 82% of trainee cases were supervised by a Consultant (10). Recurrence rates following inguinal hernia repair are significantly higher if performed by an unsupervised junior trainee; however, the addition of supervision has been shown to reduce this risk to that of a senior trainee or consultant (11). This study aimed to establish whether seniority has an impact on outcomes of AVF surgery in terms of primary patency and complications.
Methods The South Yorkshire Research Ethics Committee and Trust Research and Development granted approval for all aspects of this study. All patients who referred to the Vascular Access Service department for formation of AVF from April 2010 to June 2011 were assessed for inclusion. The baseline study assessment comprised collection of demographic data, medical and drug history and previous access history. Patients were allocated to the next available theatre list to avoid selection bias. The site for AVF formation was selected following the principles of most distal site possible, with preference for the nondominant upper limb if possible. Vessel assessment was carried out by physical examination to set criteria with selective duplex ultrasound if required as previously described (12). Surgery was performed by one of the two Consultant Vascular Surgeons (each of whom had previously performed more than 500 procedures) or one of the two unsupervised junior trainees, who had each previously performed more than 25 unsupervised AVF procedures. Participants were seen at 30, 90 and 180 days to assess patency; this comprised a clinical examination to ascertain the patency and maturity of the AVF, which was supplemented by duplex ultrasound if there was any concern regarding failure to mature or to confirm patency if no thrill was palpable. Any events related to the AVF or dialysis care were recorded prospectively by the dialysis unit and nephrology clinic staff, specifically the date of first cannulation and any complications or interventions required. Follow-up was analysed 3 years after the last surgical procedure in the cohort. Intergroup statistical analysis was carried out utilising SPSS to compare the baseline characteristics and outcomes of participants in both groups. The primary test utilized for categorical data was Pearson’s Chi-square test (13). If more than 20% of the expected frequencies were less than 5 or if
Fig. 1 - Patient pathway.
any were less than 1, then the Fisher’s exact test was utilised. Continuous data were analysed utilising Mann–Whitney U test for nonnormally distributed data.
Results A total of 106 patients were referred for AVF formation. Seventy-seven patients proceeded to undergo formation of an AVF (Fig. 1). Forty-nine (64%) procedures were carried out by a trainee. The two groups were compared in relation to patient comorbidities, past medical history, medication use, dialysis status and baseline haemoglobin measurement. No significant differences were seen between those operated on by a trainee and those by a Consultant (Tab. I). Analysis of the planned and actual site of surgery revealed that there was no difference in the location of the planned surgery and that actually performed. There was no statistically significant difference between the incidence of surgical sites when comparing Consultant and the trainee (Tab. II); however, Consultant surgeons were more likely to perform cases that were performed under general anaesthesia (p = 0.0039). The primary failure rate within our cohort was 28.6%. No statistically significant difference was found in failure or © 2015 Wichtig Publishing
Barnes et al
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Table I - Demographics and comorbidities
% male gender Age (mean) Pathology causing renal failure - Unknown - Diabetic nephropathy - Hypertensive nephropathy - Polycystic kidneys - Drug/contrast nephropathy - IgA Nephropathy - Renal cell carcinoma - Wegeners - Good pastures - Calculi/obstructive nephropathy - Acute renal injury (surgery/illness) - Interstitial nephritis % Diabetes Hypertension Smoking status: None or quit >10 years Quit less than 10 years Current 10/day Previous DVT Pacemaker Dialysis status (n): Current HD Current PD Expected dialysis in
