SAN DIEGO – Neither fish oil nor aspirin can be recommended for prevention of primary arteriovenous fistula failure in patients with advanced renal disease, a randomized trial showed.
“AVF failure increases patient morbidity and health provider costs,” Dr. Ashley B. Irish said during a press briefing at a meeting sponsored by the American Society of Nephrology. “Therefore, therapies to reduce AVF failure may reduce patient outcomes and reduce costs. But it remains uncertain whether targeting antiplatelet agents to affect thrombosis is going to improve the numbers of AVFs you can actually use.”
In a randomized trial known as Fish Oils and Aspirin in Vascular Access Outcomes in Renal Disease (FAVOURED), Dr. Irish and his associates set out to determine whether omega-3 polyunsaturated fatty acids (fish oil) can reduce new AVF access failure at 12 months. The secondary outcome was to determine if aspirin would have the same effect.
Doug Brunk/Frontline Medical News
Dr. Ashley B. Irish
The intervention consisted of 12 weeks of fish oil 4 g or placebo (olive oil) divided in two doses. A subset of patients were randomized to aspirin 100 mg or matching placebo in addition to fish oil or placebo in a factorial design, said Dr, Irish, of the department of nephrology at Fiona Stanley Hospital, Perth, Australia. AVF failure was defined as AVF thrombosis and/or abandonment and/or cannulation formation.
The study was carried out at centers in Australia, Malaysia, and the United Kingdom, and included 567 patients with stage 4 or stage 5 chronic kidney disease who were either on dialysis or who were expected to start within 12 months. Their mean age was 55 years, 63% were male, 46% had diabetes, but only 16% were on vascular dialysis. “So, these patients were a little bit healthier than you might expect in usual populations of people on dialysis,” Dr. Irish said.
The researchers found that fish oil had no effect on preventing AVF failure. In fact, 47% of patients who received fish oil had a failed AVF at 12 months, compared with 47% of those who received placebo (relative risk after adjusting for aspirin use was 1.03).
“So, nearly half of all patients in this trial had no usable AVF at 12 months after surgery,” Dr. Irish said. “It didn’t matter whether you were old or young, had vascular disease, or were diabetic or not. Fish oil didn’t help.”
Aspirin didn’t work, either. In fact, 45% of those who received aspirin had a failed AVF at 12 months, compared with 43% of those who received placebo (RR, 1.05).
Dr. Irish noted that the proportion of serious adverse events was low and similar between patients who received fish oil and those who received or aspirin. “The treatment was safe; it just didn’t work,” he said.
“This study and others have shown that trying to prevent AVFs from clotting or promoting their development by inhibiting platelets and blood vessel changes is not effective,” Dr. Irish explained. “The focus might need to shift to other strategies, such as preserving blood vessels from damage, surgical techniques, and modification of vessel walls by infrared and other pharmacological treatments.”
Dr. Irish characterized the study results as “disappointing, because these therapies are cheap, safe, and readily available. But it’s not a waste of time, because now we know that this avenue of approach in research is not going to lead us anywhere. It’s time to move on. This information will help us inform practice and plan new trials.”
The researchers reported having no financial disclosures.