Kidney disease in the elderly: biopsy based data from 14 renal centers in Poland

BACKGROUND Longer life expectancy is associated with an increasing prevalence of kidney disease. Aging itself may cause renal damage, but the spectrum of kidney disorders that affect elderly patients is diverse. Few studies, mostly form US, Asia and West Europe found differences in the prevalence of some types of kidney diseases between elderly and younger patients based on renal biopsy findings, with varied proportion between glomerulopathies and arterionephrosclerosis as a dominant injury found. Here, for the first time in Eastern Europe we analyzed native kidney biopsy findings and their relationship to clinical characteristics at the time of biopsy in elderly individuals (aged ≥65) in comparison to younger adults (aged 18-64). METHODS Biopsy and clinical data from 352 patients aged ≥65 were retrospectively identified, analyzed and compared with a control group of 2214 individuals aged 18-64. All kidney biopsies studied were examined at Medical University of Warsaw in years 2009-14. RESULTS In elderly patients the leading indication for biopsy was nephrotic range proteinuria without hematuria (34.2%) and the most prevalent pathologic diagnoses were: membranous glomerulonephritis (MGN) (18.2%), focal segmental glomerulosclerosis (FSGS) (17.3%) amyloidosis (13.9%) and pauci immune glomerulonephritis (12.8%). Hypertension and age-related lesions very rarely were found an exclusive or dominant finding in a kidney biopsy (1.7%) and a cause of proteinuria (1.1%) in elderly individuals. There were 18.2% diabetics among elderly individuals, and as much as 75% of them had no morphologic signs of diabetic kidney disease in the renal biopsy. Amyloidosis, MGN, pauci immune GN, crescentic GN and light and/or heavy chain deposition disease (LCDD/HCDD) were more frequent whereas IgA nephropathy (IgAN), lupus nephritis (LN) and thin basement membrane disease (TBMD) were less common among elderly than in younger patients. CONCLUSIONS Proteinuria, a dominating manifestation in elderly patients subjected to kidney biopsy was most commonly related to glomerulopathies. The relatively high prevalence of potentially curative kidney diseases in elderly individuals implicates the importance of renal biopsy in these patients.