Twenty-one trials were included in the review. Study designs were not reported clearly but the authors included RCTs and clinical trials. Studies had a score of 3 or higher on the Jadad scale.
Cardiovascular events (14 trials; 45,285 participants): Omega-3 fatty acid statistically significantly reduced the number of cardiovascular events compared to controls (OR 0.90, 95% CI 0.85 to 0.96; Ι²=53%).
Total mortality (17 trials; 50,468 participants): There were no statistically significant differences in total mortality between treatment groups (Ι²=28%).
Cardiac death (13 trials; 46,737 participants): Omega-3 fatty acids showed lower cardiac related deaths compared to controls but this was only just significant (OR 0.91, 95% CI 0.83 to 0.99; Ι²=32%).
Coronary events (12 trials; 41,560 participants): Omega-3 fatty acids resulted in statistically significantly fewer coronary events compared to controls (OR 0.82, 95% CI 0.75 to 0.90; Ι²=0%).
Sensitivity analysis removed the trial that caused most statistical heterogeneity not only reduced heterogeneity but also increased all the significant findings. Findings on total mortality became slightly significant in favour of omega-3 fatty acids (OR 0.93, 95% CI 0.87 to 0.99).