Background

There are conflicting data regarding the benefits of omega-3 (n-3) fatty acids, most recently in patients with type 2 diabetes.

Objective

Our goal was to evaluate the impact of licensed, highly purified n-3 fatty acids on all-cause mortality after myocardial infarction (MI).

Methods

This was a retrospective, matched-cohort study using data from the General Practice Research Database. Patients initiating treatment with 1 g of n-3 fatty acids in the 90 days after first MI were identified and each matched to 4 nonexposed patients. Progression to death was compared using time-dependent Cox models to account for potential differences in exposure to other cardiovascular risk–modifying treatments.

Results

A total of 2466 eligible subjects exposed to n-3 fatty acids were matched. The majority of patients had concurrent treatment with lipid-lowering therapies, antihypertensives, and antiplatelets after first MI, with subjects exposed to n-3 fatty acids having a greater likelihood of concurrent exposure. For those initiating n-3 fatty acids within 90 days of first MI, the adjusted hazard ratio (aHR) was 0.782 (95% CI, 0.641–0.995; P = 0.0159); for those initiating treatment within 14 days, the aHR was 0.680 (95% CI, 0.481–0.961; P = 0.0288). In patients with type 2 diabetes at baseline, the aHRs were 0.714 (95% CI, 0.454–1.124) and 0.597 (95% CI, 0.295–1.211) when initiation was within 90 and 14 days, respectively. Use of n-3 fatty acids resulted in a consistent survival benefit under a range of scenarios quantitatively consistent with the overall effect.

Conclusion

After MI, early treatment with licensed n-3 fatty acids was associated with improvement in all-cause mortality in patients with and without type 2 diabetes, against a background of contemporary cardiovascular risk–modifying treatments.