Eight RCTs (2,687 patients, range 93 to 1,516) were included in the review. Trials scored between 2 and the maximum possible 5 points on the Jadad scale; four studies reported adequate methods of random sequence generation and only two reported allocation concealment. Two studies were of an open-label design and were considered to have a high risk of bias due to the lack of blinding.
Perioperative supplementation of fish oil did not significantly reduce incidence of POAF (RR 0.86, 95% CI 0.71 to 1.03; Ι²=50%) or length of hospitalisation after surgery (WMD 0.10 days, 95% CI -0.48 to 0.67 days; Ι²=69%). No studies reported serious adverse events associated with fish oil supplementation and there was no significant effect on perioperative mortality, incidence of major bleeding or length of stay in the intensive care unit.
Meta-regression and subgroup analyses suggested possibly larger benefits with higher doses of docosahexaenoic acid (DHA): fish oil significantly reduced incidence of POAF in trials of supplements with DHA above 1g/day but not in trials with lower doses of DHA.