#2776 KIDNEY INVOLVEMENT IN PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: Monova Daniela Valentinova , Todorov Todor , Monov Simeon 
Published: June 2023

Abstract

Background and Aims
In rheumatoid arthritis (RA) kidney is commonly affected organ with clinical presentation characterized by proteinuria and microalbuminuria, followed by chronic renal failure. RA is associated with reduced kidney function, possibly due to chronic inflammation or the use of nephrotoxic therapies. Renal diseases occurring in patients with RA may have a variable clinicopathological picture. Little is known about the effects of using the novel biological agents on the risk of kidney diseases.
The aim of this study was to determine the relationship between effect of therapy and kidney involvement in patients with RA and evaluated the histopathological findings and associated clinical manifestation.

Method
In this retrospective study 275 patients with diagnosis of RA were included. In 48 patients renal biopsy was performed. The patients were divided in three groups according to changes in management of RA: 1991-2001, 2002-2011 and 2012-2022 year. Data of demographic characteristics, clinical symptoms and pathological diagnosis were extracted from medical records and pathological reports.

Results
In our study amyloidosis was the most common histologic pattern, followed by chronic glomerulonephritis (GN) and tubulointerstitial nephritis. Renal amyloidosis was diagnosed in 13 patients, membranous GN – in 9, mesangioproliferative GN – in 7 patients, focal segmental necrotizing GN – in 5, focal segmental sclerosis – in 4, minimal change disease – in 3, tubulointerstitial nephritis – in 7 patients. Between 1991 and 2001 year the most common clinical manifestation was nephrotic syndrome and the most common histopathological findings – renal amyloidosis, followed by membranous GN and focal segmental necrotizing GN. The membranous GN was related to the use of gold and its frequency decreased after 2001. The mesangioproliferative GN was the leading cause of kidney disease between 2002–2011 years and focal segmental sclerosis – between 2012–2022. In our study 68 patients had a decrease of glomerular filtration rate (GFR) &lt; 60 mL/min/m2. No kidney biopsies were performed in these cases because no urine abnormalities were detected. We found that age, duration of the disease, arterial hypertension, C-reactive protein were significant risk factors for GFR decline in patients with RA. Patients with RA who are treated with biologic agents are less likely to experience progressive decline in kidney function than those not receiving biologic treatment (hazard ratios {HRs] [95% CI], 0,84 [0,68-1,02]}.

Conclusion
In all patients with RA, renal function should be monitored and in the case of pathologic results, renal biopsy should be performed. In RA patients with renal disorder, suspected causal drug should be removed from the treatment and specific immunosuppressive therapy initiated. Improved pain management associated with biologic treatment may help to reduce the need for potentially nephrotoxic anti-inflammatory agents such as NSAIDs and certain types of non-biologic DMARDs, which could consequently reduce the risk of drug-induced nephrotoxicity and thereby contribute to the lower risk of renal diseases.