Experience With Arteriovenous Fistulae in Long Term Haemodialysis Patients at the Kenyatta National Hospital

Abstract

Background: Arteriovenous fistulae (AVF) are associated with fewer long-term events such as thrombosis, loss of primary patency and interventions, and should therefore be considered the vascular access of choice for HD whenever feasible. However, like any other vascular access, AVF are prone to a myriad of complications and varying rates of dysfunction. The number of patients on long term HD in Kenya has exponentially increased from 120 in 1995 to 2300 in 2017 and 4800 in 2020. In an attempt to increase AVF access among HD patients and reduce the number of patients on maintenance HD using central venous catheters (CVC), AVF surgery activities in KNH were up scaled through fistula camps in 2018 and 2019 and regular AVF surgeries and clinics in 2021. There are large international variations on experiences and outcomes of AVFs for hemodialysis with limited data from Africa. At the KNH, there is no structured system of following up patients after arteriovenous fistula creation, therefore the anatomical sites of AVF placement and their outcomes remain largely unknown. Objectives: The objectives of this study were to describe sociodemographic and clinical characteristics of patients who underwent AVF creation surgery during the 2018 and 2019 AVF camps at the KNH, document the anatomical sites and describe the outcomes of AVFs created during this period at the KNH. Methodology: This was an ambispective observational study of the outcomes of AVFs placed during the 2018 and 2019 AVF surgery camps at the KNH. Data on the patients’ sociodemographic and clinical characteristics, vascular access history, anatomical location of the AVF under study, date of first successful AVF cannulation and functional status of the AVF at the time of the study was collected and analyzed. Data management and analysis: Data was entered into a pre-programmed Statistical Package for Social Sciences (SPSS®) version 21.0 with which statistical analyses were performed. Continuous variables were summarized into means, modes and median. Categorical variables were summarized into xii frequencies. Fishers exact and Chi-square test of association were used to test for significant clinical associations. All statistical tests were done at 95% level of confidence where p-value <0.05 was considered significant. Results: Data from 95 participants who underwent AVF creation surgery at the Kenyatta National Hospital was analyzed. Majority were male 56 (58.9%). Their median age was 43.0 years (range from 18 – 82 years). Hypertension was the most frequent cause of ESKD 71(74.7%), followed by diabetes 28(29.5) and chronic glomerulonephritis 22 (23.2). Their median hemodialysis vintage was 8 months. The incident hemodialysis vascular access was acute internal jugular catheter in 31(32.6), subclavian vein catheter in 29(30.5%) and cuffed tunneled catheter in 24 (25.3%). Only 2(2.1) participants were initiated on hemodialysis using AVF. Brachiocephalic AVF was created in 53(55.8%) and radio cephalic AVF in 40(42.1%) of the participants. Successful primary AVF maturation was reported in 54(56.8%) and primary AVF failure in 41(43.2%). The median time from creation to cannulation was 8 weeks. Arteriovenous fistula patency was 47(87.0) at 6 months and 45(83.3%) at one year. Only the incident vascular access was significantly associated with primary AVF maturation or failure. Conclusion: This study revealed a low uptake of AVF for incident hemodialysis, central venous catheters were preferred for initiation and maintenance of hemodialysis. Brachiocephalic anastomosis was preferred in majority of the participants. This raises a concern over future vascular access options for this young population of patients. The AVF primary failure rate was comparable to the rest of the world and AVF survival at 6 months and 1 year was good. However electronic medical records and AVF surveillance protocols would enable early identification of fistulas at risk of non-maturation for for timely referral and intervention.