CLINICAL AND HISTOPATHOLOGIC ASSOCIATIONS WITH IMPAIRED RENAL-FUNCTION IN IGA NEPHROPATHY

A multicenter, double-blind, placebo-controlled, randomized trial of f ish oil in proteinuric patients with IgA nephropathy is being conducte d by the Mayo Nephrology Collaborative Group. We completed enrollment of 106 patients into the trial in December 1991. The treatment period is for two years. Hypertension is being managed in all patients with e nalapril maleate (Vasotec). We evaluated the associations between a va riety of clinical and renal morphologic features and renal function at the entry of all enrolled patients. Among 78 males and 28 females [ag e (x +/- SD) 36 +/- 14 years], older age at treatment randomization, h ypertension, at disease discovery as well as at study entry, increased fractional excretion of albumin, increased serum triglyceride levels, and more severe tubulointerstitial, vascular, and combined glomerular and tubulointerstitial histologic lesions were all univariately assoc iated (p less than or equal to 0.01) with poorer renal function measur ed by reciprocal serum creatinine and creatinine clearance levels. In a multiple regression analysis used to predict baseline reciprocal cre atinine, the best final model (R(2) = 0.48) included male sex (p <.001 ), hypertension at treatment randomization (p =.001), decreased periph eral blood erythrocytes (p =.001), increased tubulointerstitial score (p =.004), and increased fractional excretion of albumin (p =.025) as independent predictors of decreased kidney function. These association s are similar to those seen in the high-risk subset of patients with I gA nephropathy who develop end-stage renal disease. In the eventual ou tcome analysis of the clinical trial, we will examine the effects of t reatment on the two potentially modifiable risk factors, hypertension and proteinuria, on renal function.