Omega-3 oil does not reduce serious cardiovascular events for patients with diabetes mellitus (ASCEND)

Référence

The ASCEND Study Collaborative Group, Bowman L, Mafham M, et al. Effects of n-3 fatty acid supplements in diabetes mellitus. N Engl J Med 2018;379(16):1540-1550.

Sommaire

This study recruited adults 40 years and older with diabetes mellitus, no known cardiovascular disease, no contraindications to aspirin, and no major comorbidity that would keep them from participating in the study for at least 5 years. After a placebo run-in period to assure adherence, 15,480 participants were randomized to receive omega-3 fatty acids or placebo (olive oil) in identical 1-gram capsules. This was a factorial design study with patients also randomized to receive aspirin; those results are reported separately. The groups were balanced at the start of the study: the patients had a mean age of 63 years, 63% were men, and 96% were white. Almost all (94%) had type 2 diabetes mellitus. A validated risk score determined that approximately 40% of participants were at low risk of vascular events (< 5% at 5 years), 40% had a 5-year risk of 5% to 10%, and the remainder were at high risk. The primary outcome was a composite of nonfatal myocardial infarction (MI), nonfatal stroke (excluding hemorrhagic stroke), vascular death, or transient ischemic attack (TIA). TIA was added after recruitment had begun, and the length of the trial was increased after lower-than-expected rates of the composite outcome were observed. Although the authors don't specifically state that the analysis was by intention to treat, for all practical purposes it was, since 99.1% of patients had complete follow-up. After a mean of 7.4 years follow-up, there was no difference between groups for the primary composite outcome (8.9% in the omega-3 group and 9.2% in the placebo group; hazard ratio [HR] 0.97, 95% CI 0.87 - 1.08). There was no differences for any of the individual components of the composite, with the exception of vascular deaths (2.4% for omega-3 vs 2.9% for placebo; HR 0.81, 0.67 - 0.99; number needed to treat = 200 for 7.4 years). All-cause mortality also did not differ significantly between groups, although the absolute difference of 0.5% mirored that for the subset of vascular deaths.