Effects of Combination Therapy with Renin-Angiotensin System Inhibitors and Eicosapentaenoic Acid on IgA Nephropathy

Abstract

The beneficial effects of renin-angiotensin-aldosterone system inhibitors (RASI) and the omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) on IgA nephropathy (IgAN) have been reported. However, it is unknown whether these agents have any synergistic interactions. We divided 38 IgAN patients into two groups: an EPA group (n=18) treated with RASI plus EPA and a DILAZEP group (n=20) treated with RASI plus dilazep dihydrochloride. We analyzed the clinical and histological background of each patient, any relevant clinical findings obtained one year after treatment and any factors significantly related to decreases in proteinuria. The clinical findings were largely similar between the groups, except for body mass index (24.9±4.5 in the EPA group vs. 21.4±2.1 in the DILAZEP group, p=0.0041) and total cholesterol (median: 206.0 vs. 177.5 mg/dL, p=0.0493). The histological findings, evaluated according to the Oxford classification, were also similar between the groups. At one year after treatment, the EPA group demonstrated a significantly decreased mean blood pressure (from 94.7±9.0 to 86.4±7.2 mmHg, p=0.0007) and a significantly decreased median level of proteinuria (from 0.80 to 0.41 g/g creatinine, p<0.001). In the DILAZEP group, the mean blood pressure significantly decreased (from 95.2±13.2 to 88.1±7.7 mmHg, p<0.001) without any significant decrease in the median level of proteinuria (from 0.88 to 0.60 g/g creatinine). According to a multivariate logistic analysis, EPA was found to be the only independent factor related to decreases in proteinuria (odds ratio = 5.073, 95% CI: 1.18-26.7, p=0.0285). We conclude that EPA accelerates the effects of RASI and thus decreases the proteinuria observed in patients with IgAN.