1. In this multi-center, international, randomized, controlled trial, use of fish oil supplementatio at the time of arteriovenous fistula (AVF) creation was not associated with reduced risk of AVF thrombosis, abandonment, or cannulation failure.
2. Amongst patients not already on an anti-platelet agent, addition of low-dose aspirin also did not reduce risk of AVF failure. There was no observed beneficial interaction between fish oil supplementation and aspirin use.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Hemodialysis remains the most common renal replacement option for patients with end stage renal disease. Arteriovenous fistulas (AVFs) are the preferred method of vascular access due to the lower long-term complication rates compared to grafts/central venous lines. The rate of maturation failure or thrombosis for AVFs are high (20-50%). This study evaluated the effects of fish oil and low-dose aspirin at the time of AVF creation on the risk of primary AVF failure. The study was amended to focus on fish oil supplementation as many patients were on anti-platelet agents for other indications.
The results of this study showed that there was no difference in AVF thrombosis, abandonment, or cannulation failure based on supplementation with fish oil or low-dose aspirin. There was no significant interaction between fish oil supplementation and aspirin use. Although the study design was strong (multi-center, randomized, controlled), it had several challenges. There were significant exclusion criteria (those taking anti-platelet agents, anticoagulants, NSAIDs, or those with high bleeding risk). This resulted in a skewed study population that was young and had limited comorbidities. Additionally, there was missing data in one-fifth of the study population, mostly due to patients not initiating dialysis and cannulation failure not being assessed. Lastly, the study was stopped prior to reaching the target sample size due to lack of observed benefit.
In-Depth [randomized controlled trial]: The Fatty Acids and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) trial evaluated the use of fish oil supplements (2 g twice daily of eicosapenaechoic acid/docosahexaenoic acid capsules) with or without aspirin (100 mg daily) for three months starting the day before AVF creation. This study was originally conceived as a 2×2 randomized control trial; however, due to many patients needing anti-platelet therapy for other indications the protocol was amended to focus on fish oil supplementation. Patients were included if they were >19 years old, had stage 4-5 chronic kidney disease, and were going to receive hemodialysis within 12 months of AVF creation. Patients were excluded if they had increased bleeding risk (anticoagulation, thrombocytopenia, liver dysfunction), were already taking aspirin or fish oil, or were taking an NSAID or other antiplatelet agents. Study outcomes were AVF access failure at 12 months defined as AVF thrombosis, abandonment (no further use/intervention), or cannulation failure (unable to cannulate for 8 of 12 consecutive HD sessions).
A total of 536 patients were included in the analysis from 1415 initially deemed eligible. Of the 536 patients, 406 were included in the aspirin randomization cohort. Mean age was 54.8 [SD 14.3] years and 63% were male. For fish oil supplementation there was no difference in fistula failure (47% vs. 47%, p = 0.78), thrombosis (22% vs. 23%, p = 0.90), abandonment (19% vs. 22%, p = 0.43), or cannulation failure (40% vs. 39%, p = 0.81). For the aspirin subgroup there was also no difference in AVF failure (45% vs. 43%, p = 0.68), thrombosis (20% vs. 18%, p = 0.70), abandonment (24% vs. 18%, p = 0.17), or cannulation failure (38% vs. 38%, p = 0.92). Data on outcomes was missing for 22% of patients, with 2/3 of missing data due to cannulation failure not being assessed as patients did not go for hemodialysis within the 12-month limit.
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