By Serena Gordon
Meanwhile, a second set of studies discovered the news was just as grim for those with diabetes, as a higher risk for serious bleeding canceled out a modest benefit.
"Aspirin has been our 'go-to;' it's cheap and easy to get. But the benefit here was negated by the bleeding [in the diabetes study]," said Dr. James Catanese, chief of cardiology at Northern Westchester Hospital in Mount Kisco, N.Y. "We may need a better blood thinner."
In the first study, researchers led by Dr. J. Michael Gaziano, a preventive cardiologist at Brigham and Women's Hospital in Boston, followed more than 12,500 participants who took either 100 milligrams of aspirin or a placebo every day. All had some other risk factor for possible heart trouble.
After five years, the rate of events such as heart attack and stroke were virtually equal in both groups -- 269 patients (4.3 percent) in the aspirin group and 281 patients (4.5 percent) in the placebo group. The study was funded by Bayer Co. and published Aug. 26 in The Lancet.
In the diabetes research, which was reported by British researchers as two studies in the Aug. 26 issue of the New England Journal of Medicine, people with diabetes were randomly chosen to follow one of four treatments.
One group received 1 gram of fish oil and 100 milligrams of aspirin daily. Another group received fish oil and a placebo instead of aspirin. The third group was given a placebo (filled with olive oil) for fish oil and received active aspirin. The final group received two placebos.
The average follow-up time was nearly 7.5 years. During that time, 8.9 percent of those given the fish oil and 9.2 percent of those given a fish oil placebo had serious vascular events, such as a heart attack or stroke. Death rates were also similar between the two groups. Both studies received funding from the British Heart Foundation and Bayer.
"Aspirin and fish oil are not a panacea to prevent cardiovascular disease in people with diabetes," said Dr. Joel Zonszein, director of the Clinical Diabetes Center at Montefiore Medical Center in New York City.
"My message to people with diabetes is that treating high blood pressure, abnormal cholesterol and high blood sugar from the get-go -- along with healthy lifestyle changes -- is important," said Zonszein, who was not involved in the research.
Dr. Louise Bowman, who led the fish oil study, said, "Previous research has shown no benefit of fish oil supplements for other types of patients at increased risk of cardiovascular events. Our findings are in line with this, and so we don't believe that there is any justification for recommending fish oil supplements to protect against cardiovascular events."
She added that other studies have shown that there doesn't appear to be a benefit to fish oil supplements for people who've already had a heart attack either. Bowman is a professor of medicine and clinical trials at Oxford University's Nuffield Department of Population Health in England.
Aspirin fared somewhat better among those with diabetes. The rate of serious vascular events was 8.5 percent for people taking aspirin and 9.6 percent for those taking a placebo. That means aspirin reduced the risk of a serious event by 12 percent.
However, that good news was countered by the risk of major bleeding. Slightly over 4 percent of people taking aspirin had a major bleeding event (including bleeding in the brain, eye and digestive system). Just 3.2 percent of those taking a placebo had any serious bleeding. Aspirin increased the risk of bleeding by 29 percent, the study found.
Dr. Jane Armitage, senior author of the aspirin/diabetes study, said, "We showed clearly that aspirin reduces the risk of vascular events, including heart attacks, strokes, and mini-strokes; however, it also increased the risk of major bleeds, mainly from the GI tract, so overall there was no clear benefit."
Armitage said the finding provides "much needed clarity" about whether or not to recommend aspirin to people with diabetes who haven't had a heart attack. She said for people already taking known safe treatments such as cholesterol and blood pressure medicine to prevent heart disease and stroke, "there is no added benefit of taking aspirin."
Armitage noted that aspirin is still recommended for people who've already had events such as a heart attack or stroke. She is a professor of clinical trials and epidemiology at Oxford University.
Catanese, who wasn't involved in any of the studies, said he wasn't surprised by the fish oil findings.
"I think there's a benefit to eating fish, not just fish oil. There's something in the food that we may not be able to put in a pill or a capsule," he said.
Like Zonszein, Catanese recommended that people with diabetes eat a healthy diet, exercise regularly and keep good control of their diabetes to prevent heart disease. Control of cholesterol and blood pressure is also very important for people with diabetes, he said.
The findings were presented Sunday at the European Society of Cardiology annual meeting, in Munich, Germany.