FISH-OIL IN LUPUS NEPHRITIS - CLINICAL FINDINGS AND METHODOLOGICAL IMPLICATIONS

Our objective was to determine the effects of fish oil on renal functi on, symptoms, and serum lipids in patients with lupus nephritis. A dou ble-blind, randomized crossover trial of fish oil versus placebo (oliv e oil) was done on 26 patients with confirmed systemic lupus; 21 compl eted the study. Intervention was fish oil or placebo, 15 g/day, for on e year followed by a 10 week wash-out period, and then the reverse tre atment for one year. At baseline and six month intervals, we measured platelet membrane fatty acids, indices of renal function, a disease ac tivity index, serum lipid levels, blood pressure, serum viscosity and red cell flexibility. We found that platelet membrane phospholipids we re uniformly affected by fish oil supplementation (P < 0.001) but with significant carry-over effects despite a 10 week wash-out period. Glo merular filtration rate and serum creatinine were not affected. A non- significant reduction in mean (SE) 24-hour proteinuria occurred, from 1424.1 mg (442.7) on placebo to 896.7 mg (352.2) on fish oil (P = 0.21 ). Fish oil lowered serum triglycerides from 1.89 (0.25) mmol/liter to 1.02 (0.11) mmol/liter (P = 0.004). VLDL cholesterol decreased marked ly whether patients initially received fish oil or placebo (P = 0.004) . The size of the reduction was affected by the order of treatment (P = 0.03), but parallel comparisons were significant before the crossove r (P = 0.0006). With the possible exception of bleeding time, no other treatment effects were shown with fish oil. However, treatment order effects were seen in urinary IgG excretion (P = 0.03), whole blood vis cosity (P < 0.0001), red cell flexibility (P = 0.004), and bleeding ti me (P = 0.06). In conclusion, one year of dietary supplementation with fish oil in patients with stable lupus nephritis did not improve rena l function or reduce disease activity, but did alter some lipid parame ters. Hitherto unreported carry-over effects and treatment order effec ts caused by the olive oil created a risk of type II error, and bear m ethodologic consideration in the design of future studies.