P0823CHARACTERISATION OF HISTOLOGY PROVEN GLOMERULAR DISEASES IN THE MALTESE POPULATION: A NATIONAL CROSS-SECTIONAL SURVEY
Authors: Micallef Sarah , Balzan Deborah , Bugeja Maria , Buttigieg Jesmar , Farrugia Emanuel 
Published: June 2020

Abstract

Background and Aims
The incidence and characterisation of glomerular diseases in Malta has not been investigated. This survey aims at determining the nationwide patterns, incidence and spectrum of biopsy-proven glomerular diseases.

Method
This is a retrospective analysis of all native kidney biopsy specimens performed in the adult population in Malta between January 2014 and December 2018. Demographic data and clinical variables were extracted from histopathology reports. Pathological diagnosis was based on findings obtained through light microscopy, immunofluorescence and electron microscopy.

Results
A total of 281 sufficiently sampled and conclusive native kidney biopsies were performed in Malta. The median age at biopsy was 52.9 years (interquartile range: 25), 58.7% were males and 93.1% were Maltese patients. The most common finding on biopsy was diabetic nephropathy (13.5%, n=38). Chronic kidney disease which was progressing faster than expected was the most common reason for performing a biopsy in these cases (65.8%, n=25/38). Ischaemic glomerulopathy was seen in 13.2% of cases (n=37). Podocytopathies accounted for 19.2% (n=54) of biopsies. Focal segmental glomerulosclerosis (FSGS) was seen in 12.8% (n=36); 58.3% (n=21/36) of which considered secondary to other conditions. Minimal change disease (MCD) accounted for 5.7% (n=16), nephrotic syndrome being the most common indication for biopsy (87.5%, n=14/16). Membranous nephropathy (MN) was identified in 11.0% of biopsies (n=31). Anti-Phospholipase A2 antibody status was available for 17 of these patients, 58.8% being positive (n=10/17). Immunoglobulin A nephropathy accounted for 11.7% (n=33). An active urinary sediment was the main indication for biopsy in 78.8% of these cases (n=26/33). Thin basement membrane was present in 2.1% (n=6). Lupus nephritis (LN) was present in 5.7% (n=16) of biopsies; class III LN in 50% (n=8/16), class IV LN in 37.5% (n=6/16); features of class V lupus were present in 31.3% (n=5/16). Only one biopsy showed isolated class V LN. Systemic involvement was present in the vast majority of patients with LN (81.3%, n=13/16). Pauci-immune glomerulonephritis was identified in 5.7% (n=16) of biopsies. Microscopic polyangiitis was the commonest type of pauci-immune ANCA-positive vasculitis (75.0%, n=12/16). Anti-glomerular basement membrane (GBM) disease accounted for only 1.1% (n=3). All patients with anti-GBM disease and 37.5% (n=6/16) of ANCA-positive vasculitis developed a rapidly progressive course requiring dialysis. Interstitial nephritis accounted for 5.7% (n=16) of biopsies; 31.2% (n=5/16) attributed to drugs. Haematological disease related glomerulonephritis accounted for 2.1% (n=6), infection related glomerulonephritis 1.1% (n=3), fibrillary glomerulonephritis 1.4% (n=4), membranoproliferative glomerulonephritis 0.7% (n=2) and other pathologies 6.4% (n=18).

Conclusion
This is the first nationwide study investigating the histopathological patterns and incidence of biopsy-proven glomerular diseases in Malta. The most common biopsy-proven glomerular disease is diabetic nephropathy, followed by focal segmental glomerulosclerosis. and ischemic glomerulopathy.