Angiotensin-converting-enzyme inhibitors slow renal decline in IgA nephropathy, independent of tubulointerstitial fibrosis at presentation

Abstract

Background: Tubulointerstitial fibrosis (TIF) is a marker of progression of diabetic and non-diabetic nephropathy, correlating with creatinine clearance (CCr), and functional outcome. Angiotensin-converting-enzyme inhibitors (ACEIs) slow the rate of decline of renal function in proteinuric patients.

Aim: To examine whether ACEIs affect TIF, directly or indirectly.

Design: Prospective 3-year follow-up study.

Methods: We enrolled 49 patients with IgA nephropathy (IgAN), treating some with ACE inhibitors (n = 26, 1-2 mg/day temocapril or trandolapril) and some with calcium-channel blockers (CCB, n = 23, 2.5-5 mg/day amlodipine). Blood pressure, serum creatinine, and urinalysis were measured monthly, and 24-h endogenous creatinine clearance (CCr) at least once a year.

Results: In the CCB group, TIF was positively correlated with the rate of decline in CCr (dCCr), consistent with previous observations. In the ACEI group, dCCr was lower (0.02 +/- 0.02 vs. 0.06 +/- 0.03), and the TIF-dCCr correlation was absent.

Discussion: In the absence of post-treatment histological data, it is not possible to say whether ACEIs have an effect on TIF. However, ACEIs appear to slow the progression of renal failure in IgAN, regardless of the degree of TIF at presentation.