The role of underlying nephropathy in the progression of renal disease

Background. Disease-specific pathogenic mechanisms may be major determinant s of the spontaneous rate of progression of chronic renal failure (CRF). To clarify the role of different underlying renal diseases, we examined the r ate of CRF progression in 886 patients with chronic nephropathies. Methods. Secondary analysis of two multicenter, prospective randomized tria ls: the Northern Italian Cooperative study (NIC) and the AIPRI study (ACE-I nhibition in Progressive Renal Insufficiency). Univariate and multivariate analyses of variance were used to select the covariates possibly related to CRF progression (estimated by means of the slope of the reciprocal of Sc, against time), focusing on the contributory role of primary renal diseases. Results. The overall rate of CRF progression was relatively low but there w as a considerable difference in the slopes relating to the underlying nephr opathy (particularly evident in the patients with chronic glomerulonephriti s (CGN)). The median rate of CRF progression in both studies was more rapid in patients with polycystic kidney disease (PKD) and CGN than in those wit h other nephropathies. Multivariate analysis showed PKD as an independent p redictor of the CRF progression rate only in the NIC Study (P < 0.0015); th e selected variables in both studies predicted a variation of only 15-18% i n the CRF progression rate. Conclusion. The underlying renal disease certainly plays a role in the natu ral history of CRF, but the variability of the CRF progression rates relate d to different renal diseases and between individuals with the same diagnos is underlines the need for caution in evaluating risk factors and predictin g single patient outcomes.