I spend a lot of time knocking supplements for not having research behind them. It’s important therefore to highlight when such research is done. From JAMA Internal Medicine, “Effect of Fish Oil Supplementation and Aspirin Use on Arteriovenous Fistula Failure in Patients Requiring Hemodialysis: A Randomized Clinical Trial“:
Importance: Vascular access dysfunction is a leading cause of morbidity and mortality in patients requiring hemodialysis. Arteriovenous fistulae are preferred over synthetic grafts and central venous catheters due to superior long-term outcomes and lower health care costs, but increasing their use is limited by early thrombosis and maturation failure. ω-3 Polyunsaturated fatty acids (fish oils) have pleiotropic effects on vascular biology and inflammation and aspirin impairs platelet aggregation, which may reduce access failure.
Objective: To determine whether fish oil supplementation (primary objective) or aspirin use (secondary objective) is effective in reducing arteriovenous fistula failure.
Design, Setting, and Participants: The Omega-3 Fatty Acids (Fish Oils) and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED) study was a randomized, double-blind, controlled clinical trial that recruited participants with stage 4 or 5 chronic kidney disease from 2008 to 2014 at 35 dialysis centers in Australia, Malaysia, New Zealand, and the United Kingdom. Participants were observed for 12 months after arteriovenous fistula creation.
Interventions: Participants were randomly allocated to receive fish oil (4 g/d) or matching placebo. A subset (n = 406) was also randomized to receive aspirin (100 mg/d) or matching placebo. Treatment started 1 day prior to surgery and continued for 12 weeks.
Main Outcomes and Measures: The primary outcome was fistula failure, a composite of fistula thrombosis and/or abandonment and/or cannulation failure, at 12 months. Secondary outcomes included the individual components of the primary outcome.
People who require hemodialysis need to have their blood cycles regularly. This often requires a permanent means for vascular access. Unfortunately, such access carries with it the risk of morbidity and mortality.
There are a number of ways to achieve permanent vascular access. In general, arteriovenous fistulae are preferred to synthetic arteriovenous grafts or central venous catheters. AVFs take longer to mature before use and have a much greater risk of early failure.
Some have theorized that omega-3 fatty acids (fish oil) can help “not only inhibiting platelet aggregation1 but also decreasing blood viscosity, improving red blood cell flexibility, promoting vasodilation, inhibiting smooth muscle cell proliferation, and reducing inflammation.” Others theorize that aspirin might do similar things.
This trial wanted to see if either of these things were true. Researchers ran a double-blinded, randomized controlled trial of participants with stage 4 or 5 kidney disease at 35 dialysis centers in Australia, Malaysia, New Zealand, and the UK. Participants were randomized to get fish oil, placebo, both, or neither. Those that could not take aspirin or who couldn’t take aspirin were excluded from the randomization for aspirin, of course. The primary outcome of interest was failure of their fistula or a failure to use the fistula.
This wasn’t a small study. Of the 1415 deemed eligible over the study period, 567 were randomized and included in the trial. Of these, 406 were randomized to get aspirin or placebo as well.
Let’s talk about fish oil first. The failure rate in both arms (intervention and placebo) was 47%. No difference at all. Fish oil didn’t reduce fistula thrombosis or cannulation failures either.
Aspirin didn’t work either. The rate of failure was 45% in the aspirin arm and 43% in the placebo arm.
I grant you that this is a pretty focused trial, for a pretty specific cause. But we should respect the process and acknowledge the efforts. Fish oil and aspirin don’t seem to percent failures of arteriovenous fistulas in the year after surgery. Own it. Consider changing your practice.