P1041KIDNEY BIOPSY IN DIABETIC PATIENTS ALLOWS A BETTER DEFINITION OF DIAGNOSIS AND OUTCOME

Abstract

Abstract Background and Aims The WHO has defined type II Diabetes Mellitus (DMII) as an epidemic disease. Indeed worldwide, diabetic patients are estimated to be 400 millions and this number is bound to grow in the next decades 1.Diabetic nephropathy (DN) develops in 20-40% of patients with DM 2.It is a condition generally characterized by presence of proteinuria and leads to a progressive reduction in kidney function and ultimately to End Stage Renal Disease (ESRD). Although DN represents a frequent complication in patients with DM it is well known that diabetic patients may develop kidney disease due to any other cause. Several studies have shown that about 30% of diabetic patients undergoing a kidney biopsy will be diagnosed with a non diabetic renal disease ( NDRD) 3.This suggests the importance of kidney biopsy in patients with DM.. Aim of our study was to evaluate the frequency of NDRD in our population, to identify pre-existing clinical or humoral parameters in patients with histological diagnosis of DN vs NDRD also evaluating the different clinical outcomes in patients with diagnosis of DN vs NDRD and identifying histological patterns of DN which may be associated to worst clinical outcomes. Method In this single centre retrospective observational study we evaluated all type II diabetic patients having undergone kidney biopsy in ICS Maugeri Spa SB in Pavia from May 2002 to December 2018 Results Our population included 71 patients with diagnosis of DMII having undergone kidney biopsy. Among these 36 (51%) had a histological diagnosis of DN, 29 ( 40%) of NDRD and 6 ( 9%) had both DN+NDRD. Of the NDRD patients 21% were diagnosed with membranous nephropathy 17% with nephroangiosclerosis, 10% with focal segmental glomerulosclerosis and 10% acute tubular necrosis.We found DN patients compared to NDRD had a greater DM II vintage (12 years vs 9,5 years), higher HbA1C (7,4% vs 6,5%, p<0.001), were more frequently on insulin( 67% vs 14%, p<0.002) and were more frequently affected by diabetic retinopathy ( 89% vs 3,5% p<0.001)There was no difference between DN and NDRD in terms of hypertension diagnosis or degree and proteinuria or creatinine value at biopsy ( proteinuria median value in both groups 3 g/24 h and creatinine DN (1,48 mg/dL), vs NDRD (1,43 mg/dL)).Interestingly, 24 months post biopsy however proteinuria values in NDRD reduced significantly while remaining stable in DN, with a significant difference from DN at 24 months ( p<0.018). Consistently with this data also creatinine values were higher in DN vs NDRD. We postulated this could be a consequence of targeted therapeutic intervention in NDRD .We next evaluated in DN the exhistence of a correlation between degree of histological damage and clinical outcome.We analyzed biopsies from 10 DN patients having a follow up of at least 24 months and assigned to each a score based on degree of glomerulosclerosis (0-3), tubulointerstitial(0-5) and vascular damage (0-5). Our data shows a correlation between severity of glomerular damage ( score>2) and worsening of proteinuria and creatinine over a 24 month period although not statistically significant probably due to small sample size Conclusion In a population of DMII patients undergoing kidney biopsy 40% of patients had NDRD. NDRD appeared to have better clinical outcome ( lower proteinuria and lower creatinine) over time probably as a result of targeted therapy, also degree of gloerular damage in DN correlated with worse prognosis. Although some pre-exhisting conditions such as diabetic retinopathy are highly predictable of DN diagnosis our data supports the essential role of kidney biopsy in diabetic patients.Alltogether our data demonstrates the value of performing kidney biopsy in DMII patients