HealthDay News — Omega-3 (n-3) fatty acids did not reduce the rate of cardiovascular events in high-risk patients with prediabetes or diabetes during a six-year follow-up period, results from the ORIGIN trail show. 

Cardiovascular mortality was similar among patients randomly assigned to n-3 fatty acids or placebo (9.1% vs. 9.3%, respectively), Jackie Bosch, MSc, from McMaster University and Hamilton Health Sciences in Hamilton, Ontario, and colleagues reported at the American Diabetes Association meeting.

Supplementation with n-3 fatty acids also did not reduce the rate of major vascular events (16.5% versus 16.3%) or all-cause death (15.1% versus 15.4%).

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The researchers found no differences in Kaplan Meier curves between the two groups for death from CV causes (HR=0.98; 95%: CI 0.87-1.10; P=0.72); a composite of myocardial infarction, stroke or CV death (HR=1.01; 95% CI: 0.93-1.10, P=0.81); all-cause death (HR=0.98; 95% CI: 0.89-1.07; P=0.63); and death from arrhythmia (HR=1.10; 95% CI: 0.93-1.30; P=0.26).

They also analyzed outcomes including fatal and nonfatal MI; fatal and nonfatal stroke; heart failure hospitalization, revascularization; limb or digit amputation and hospitalization for any cardiovascular cause and found no benefit with n-3 fatty acids.

Among patients receiving n-3 fatty acids, triglyceride levels were reduced by 14.5 mg/dL more than among those receiving placebo (P < 0.001), with no significant impact on other lipids. The rates of adverse effects were similar between the groups.

These findings should not influence dietary recommendations to eat more fish, the researchers wrote in a study published in the New England Journal of Medicine to coincide with the meeting. They explained that this lifestyle choice “not only increases the intake of foods containing n–3 fatty acids but is also associated with a reduction in the consumption of foods such as red meats, which may be harmful.”

The Outcome Reduction with Initial Glargine Intervention (ORIGIN) trial involved 12,536 adults with type 2 diabetes, impaired fasting glucose or impaired glucose tolerance, whose mean age was 64 years and of whom 35% were women.

Patients assigned to the treatment arm took 1 g/day of n-3 fatty acids (Omacor), which was a combination of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The placebo was 1 g/day of olive oil. Both arms were also taking either insulin glargine or standard care.

Unlike previous studies that have shown CV benefits with fish oil, patients who participated in ORIGIN were taking other cardioprotective drugs, which may have diminished the study’s statistical power to detect the effects of n-3-fatty acids, the researchers noted.

Furthermore, other trials involved patients who had had a myocardial infarction or heart failure in the three-months prior and might have been more likely to benefit from any potential antiarrhythmic effect of n–3 fatty acids than ORIGIN participants.

The researchers suggested that the dose of n-3 fatty acids used in the study may have been too low to detect any effect.

The study was supported by Sanofi and study drugs were provided by Pronova BioPharma Norge; several researchers disclosed financial ties to pharmaceutical companies, including Sanofi.

Bosch J et al. N Engl J Med. 2012; doi: 10.1056/NEJMoa1203859.