Renal prognosis a long time after renal biopsy on patients with diabetic nephropathy

Abstract

Background: A new classification of diabetic nephropathy was reported by Tervaert et al., but the association between pathological findings and the clinical outcomes remains unclear.

Methods: Among 310 patients with diabetes mellitus who underwent renal biopsy from March 1985 to January 2010 and were confirmed to have diabetic nephropathy according to the Tervaert's classification, 205 patients were enrolled in this study. Cox proportional hazard regression analysis was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for death-censored renal death. Each regression analysis employed two levels of multivariate adjustment.

Results: After adjustment for age, gender, estimated glomerular filtration rate, type of diabetes, urinary protein excretion, systolic blood pressure, body mass index, HbA1c, diabetic retinopathy and red blood cells in urinary sediment at the time of renal biopsy, compared with glomerular class IIA, the HRs for death-censored renal death of glomerular classes I, IIB, III and IV were 0.21 (95% CI: 0.04-1.25), 2.12 (0.89-5.04), 4.23 (1.80-9.90), and 3.27 (1.32-8.10), respectively. Also, compared with an interstitial fibrosis and tubular atrophy score 1 group, HRs for score 0 group, score 2 group and score 3 group were 0.08 (0.01-0.57), 2.17 (0.96-4.91), 4.78 (1.96-11.68), respectively.

Conclusions: The progression of glomerular, tubulointerstitial and vascular lesions was associated with higher HRs for renal death. These results suggest the clinical utility of Tervaert's pathological classification.

Keywords: diabetic nephropathy; pathological classification; renal prognosis.

FIGURE 1:

Flowchart of study participants. eGFR: estimated glomerular filtration rate.

FIGURE 2:

(a) Renal survival rates in glomerular classes. The 5-year renal survival rate in our study was estimated as 100% in glomerular class I, 88.5% in class IIa, 53.3% in class IIb, 36.4% in class III and 21.2% in class IV. (b) Renal survival rates in interstitial fibrosis and tubular atrophy (IFTA) scores. (c) Renal survival rates in interstitial inflammation scores. (d) Renal survival rates in arteriolar hyalinosis scores. (e) Renal survival rates in arteriosclerosis scores. Large vessel was not obtained in 13 patients. (f) Renal survival rates in the presence or nothing of exudative lesion. Abbreviation: Median time, median time for introduction of dialysis after renal biopsy

FIGURE 3:

Univariate and multivariate Cox proportional hazard models by pathological variables at renal end point. Model 1: adjusted for age, gender, estimated glomerular filtration rate, type of diabetes, urinary protein excretion, systolic blood pressure, body mass index and HbA1c at the time of renal biopsy. Model 2: adjusted for the above plus diabetic retinopathy and red blood cells in urinary sediment at the time of renal biopsy. HR: hazard ratio, 95% CI: 95% confidence interval. G-class, glomerular class; IFTA, interstitial fibrosis and tubular atrophy scores; interinfra, interstitial inflammation scores; hyalinosis, arteriolar hyalinosis scores; A-sclerosis, arteriosclerosis scores; exudative, presence of exudative lesions.