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Omega-3 meta-analysis shows mortality benefit
Data from the GISSI-Prevenzione study (Lancet 1999;354:447–55) suggested that omega-3 fatty acids may have the ability to reduce death from cardiovascular causes, mainly through a reduction in sudden cardiac death (SCD). However, subsequent studies among patients with implantable cardiac defibrillators (ICD) failed to demonstrate any reduction in device therapy with supplemental fish oils, possibly owing to methodological limitations such as small sample size, poor patient adherence and high loss to follow-up. Furthermore, previous systematic reviews of fish oil therapy have been inconclusive but have not included some of the most recent data, such as the JELIS trial (Lancet 2007;369:1090–8).
Leon et al performed a systematic review of 12 randomised trials of fish oil supplementation, which included a total of 32 779 patients. The primary outcome of interest was the arrhythmic end point of appropriate ICD intervention and SCD. Secondary outcomes were all-cause mortality and death from cardiac causes (not specified further). Finally, subgroup analysis was performed to examine the effect of fish oil supplement formulation, either docosahexaenoic acid or eicosapentaenoic acid, or both, on death from cardiac causes.
Overall, the use of fish oil supplementation was not associated with either a reduction in the risk of appropriate ICD intervention (OR = 0.90, 95% CI 0.55 to 1.46) or a reduction in the incidence of SCD (OR = 0.81, 0.52 to 1.25). Although all-cause mortality was not affected by fish oil supplementation, a 20% reduction (OR = 0.80, 0.69 to 0.92) in death from cardiac causes was seen, mainly owing to reduced coronary events. The potential mechanism enabling fish oils to act in this way remains elusive; however, it is a possible that fish oils may stabilise atherosclerotic plaque via their anti-inflammatory influence. A dose–response relationship for effects on death from cardiac causes was not seen and therefore comment cannot be made as to …