Analysis of 65 Renal Biopsies From Patients With Rheumatoid Arthritis (1976-2015): Change in Treatment Strategies Decreased Frequency and Modified Histopathological Findings.

Introduction: No inherent renal lesions are known in rheumatoid arthritis (RA), but urinary abnormalities and renal dysfunction have been described.
Objective: First, we describe the histopathological findings of renal biopsies (RBs) in patients with RA and associated clinical manifestations. Second, we evaluated time evolution of RA and the relationship between drugs and renal disease. Last, we investigate whether changes in the management of RA from 1976 to 2015 influenced RBs indication, frequency, and type of histopathological findings.
Patients and Methods: This is a retrospective and observational study conducted at a university hospital from Argentina. Patients with a diagnosis of RA (ACR, 1987) and RBs between 1976 and 2015 were included. Sixty-five patients met the inclusion criteria. The histopathological findings and associated clinical manifestations were evaluated. Time evolution of RA and the relationship between drugs and renal disease were also determined. To clarify these issues, we characterized 3 groups according to changes in the management of RA: 1976-1989, 1990-2002, and 2003-2015.
Results: The most common histopathological finding was renal amyloidosis in 31% (n = 20), followed by mesangial glomerulonephritis in 18% (n = 12), membranous nephropathy in 17% (n = 11), extracapillary proliferative glomerulonephritis in 15% (n = 10), focal segmental glomerular sclerosis in 9% (n = 6), minimal change nephropathy in 5% (n = 3), and tubulointerstitial nephritis in 5% (n = 3). Time evolution of renal amyloidosis was significantly higher than other RBs (15 ± 12 vs 7 ± 6.5 years). Nephrotic syndrome was the most common clinical manifestation (60%) followed by hematuria (46%) with or without proteinuria. Membranous nephropathy was related to the use of gold salts in 45% of cases, and its frequency decreased since 1990. Before 2003, renal amyloidosis was the leading cause of kidney disease, but mesangial glomerulonephritis reached the same frequency between 2003 and 2015. We found that RBs decreased 20% in the second period (1990-2002) and 40% in the last period (2003-2015). Nephrotic syndrome remained the main RB indication during the entire study period.
Conclusion: This is the first report on RBs findings in patients with RA from Latin America. We found a significant reduction in RBs frequency and modified histological patterns throughout the study period, although RB indication was not modified. Changes in the management of RA might have influenced these findings.