The relationship of pathologic classification and prognosis in diabetic nephropathy

Objective To explore the relationship between clinical manifestations and pathological changes in diabetic nephropathy (DN) and to assess the predictive power of the pathologic classification for DN established by the Renal Pathology Society in 2010. Methods Patients with type 1 or type 2 diabetes and biopsy-proven DN in the Third Affiliated Hospital of Sun Yat-sen University between January 2004 to June 2014 were enrolled in the present study and were followed-up until 31 December 2014. The outcome was defined as renal end-points including renal replacement therapy and doubling of serum creatinine as well as all-cause mortality. The laboratory and histologic data were analyzed and outcomes were assessed using survival analysis. Results Fifty-seven people enrolled in this study were categorized into Class IIa (n=9), Class IIb (n=9), Class III (n=25) and Class IV (n=14) while no participants belonged to Class I. The changes of Class IIa were slight and those of Class IV were severe both in the clinical data (diabetic duration, blood pressure, estimated glomerular filtration rate, urine protein excretion rate, albumin and hemoglobin) and the pathological data (percentage of global glomerulosclerosis, percentage and scoring of interstitial fibrosis and tubular atrophy, scoring of interstitial inflammation and incidence of large vessel lesions). There were no significant differences between Class IIb and III in the above variables except for the scoring of arteriosclerosis. The mean follow-up duration was 25.9 months. Twenty-five patients (43.9%) reached the renal outcomes and six people (10.5%) reached all-cause mortality. The survival analysis showed that there were significant differences among the renal survival curves of different glomerular classes and of different interstitial and vascular scorings, but not in the survival curves related to all-cause mortality. Conclusions The glomerular classes are not completely associated with renal prognosis. The clinical manifestations and renal outcomes are benign in Class IIa, moderate but similar in Class IIb and III and severe in Class IV. The glomerular classification and interstitial and vascular scorings are associated to renal prognosis while their associations with mortality remain to be verified.