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The Omega-3 Index and relative risk for coronary heart disease mortality: Estimation from 10 cohort studies

      Highlights

      • Higher in vivo omega-3 levels are linked with lower risk for heart disease.
      • Omega-3 status is currently expressed using several different metrics.
      • The Omega-3 Index (O3I, RBC EPA + DHA) is a useful marker but cutpoints need validation.
      • Transformed data from a prior meta-analysis confirms O3I cutpoints of <4% and >8%.

      Abstract

      Background and aims

      A recent 19-cohort meta-analysis examined the relationships between biomarkers of omega-3 fatty acids and risk for coronary heart disease (CHD). That study did not, however, report hazard ratios (HRs) specifically as a function of erythrocyte eicosapentaenoic (EPA) plus docosahexaenoic (DHA) levels, a metric called the Omega-3 Index in which EPA + DHA content is expressed as a percent of total fatty acids. The Omega-3 Index has been used in several recent studies and is a validated biomarker of omega-3 fatty acid tissue levels, but additional data are needed to confirm (or refute) the originally-proposed clinical cut-points of <4% (higher risk) and 8%–12% (lower risk).

      Methods

      The present study was therefore undertaken using published data from this meta-analysis to estimate HRs per 1-SD increase in the Omega-3 Index and median quintile values for this metric across 10 of the cohorts for which the needed data were available.

      Results

      The overall mean (SD) for the Omega-3 Index in these 10 cohort studies was 6.1% (2.1%), and the HR for a 1-SD increase was 0.85 (95% confidence interval, 0.80–0.91). Median quintile 1 and 5 levels were 4.2% vs. 8.3%, respectively. Based on these values, we estimate that risk for fatal CHD would have been reduced by about 30% moving from an Omega-3 Index of 4%–8%.

      Conclusions

      These findings support the use of <4% and >8% as reasonable therapeutic targets for the Omega-3 Index.

      Keywords

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