This randomized, placebo-controlled, double-blind trial evaluated the role of prednisone and omega 3 fatty acids (O3FA) in patients with IgA nephropathy. Entry criteria were (1) biopsy-proven IgA nephropathy, (2) estimated GFR >50 ml/min per 1.73 m 2 , and (3) moderate to severe proteinuria. Thirty-three patients were randomly assigned to receive prednisone 60 mg/m 2 every other day for 3 mo, then 40 mg/m 2 every other day for 9 mo, then 30 mg/m 2 every other day for 12 mo (prednisone group); 32 were randomly assigned to receive O3FA 4 g/d for 2 yr (1.88 g eicosapentaenoic acid, 1.48 g docosahexaenoic acid; O3FA group); and 31 were randomly assigned to receive placebo (placebo group). Most (73%) patients completed 2 yr of treatment. Randomly assigned patients who were hypertensive were given enalapril 2.5 to 40 mg/d. The primary end point was time to failure, defined as estimated GFR <60% of baseline. An overall significance level of 0.10 was used. The three groups were comparable at baseline except that the O3FA group had higher urine protein to creatinine (UP/C) ratios than the placebo group (P ‫؍‬ 0.003). Neither treatment group showed benefit over the placebo group with respect to time to failure, with 14 patient failures overall (two in the prednisone group, eight in the O3FA group, and four in the placebo group). The primary factor associated with time to failure was higher baseline UP/C ratios (P ‫؍‬ 0.009). Superiority of prednisone or O3FA over placebo in slowing progression of renal disease was not demonstrated in this study. However, the relatively short follow-up period, inequality of baseline UP/C ratios, and small numbers of patients precludes definitive conclusions.

Previous studies that have evaluated fish oil preparations in patients with IgA nephropathy (IgAN) have produced a wide range of conclusions. Proposed explanations for these discordant results have not provided a unifying hypothesis. Results from two clinical trials were analyzed to examine whether there is a dosage-dependent effect of Omacor, a purified preparation of omega-3 fatty acids, in patients with IgAN. Whether changes in the level of proteinuria and plasma phospholipid fatty acid profiles were dependent on the dose of Omacor factored by body size was determined. In a post hoc analysis of the first trial results, correlations were found between (1) phospholipid eicosapentaenoic acid (EPA)/arachidonic acid (AA) and docosahexaenoic acid (DHA)/AA ratios and the dosage of Omacor, expressed as milligrams per kilogram of body weight (r ‫؍‬ 0.78, P < 0.001 for EPA/AA; r ‫؍‬ 0.86, P < 0.001 for DHA/AA), (2) phospholipid EPA/AA and DHA/AA levels and percentage change in urine protein/creatinine ratio after 21 to 24 mo of therapy (r ‫؍‬ ؊0.50, P ‫؍‬ 0.02 for EPA/AA; r ‫؍‬ ؊0.52, P ‫؍‬ 0.01 for DHA/AA), and (3) dosage of Omacor per kilogram of body weight and change in proteinuria after 21 to 24 mo (r ‫؍‬ ؊0.50, P ‫؍‬ 0.02). A similar relationship was observed between urine protein/creatinine ratio and dosage of Omacor per kilogram of body weight in trial 2 (r ‫؍‬ ؊0.38, P < 0.001). It is concluded from these data that the effect of Omacor on proteinuria in patients with IgAN is dosage dependent and is associated with a dosage-dependent effect of Omacor on plasma phospholipid EPA and DHA levels.