Evaluation of renal lesions and clinicopathologic correlation in rheumatoid arthritis

The most common causes of renal disease in rheumatoid arthritis (RA) are glomerulonephritis (GN), amyloidosis, tubulo-interstitial nephritis, and drug toxicity. Our aim was to evaluate the clinicopathologic correlation of renal lesions and to assess the course and prognosis of renal disease in patients with RA. We conducted a prospective observational study in all adult patients with RA between July 2010 and June 2015. The total number of patients studied was 90, with a female:male ratio of 2.3:1. Mean follow-up duration was 30 ± 6.5 months. About 54 patients (60%) were asymptomatic. The most common symptom was edema legs (30%), followed by oliguria (10%). About 18 patients (20%) presented with the nephrotic syndrome, 15 patients (16.6%) with nephritic syndrome, and 30 (33%) with asymptomatic urinary abnormalities. Chronic kidney disease (CKD) was seen in 48 of 90 patients (53%).The most common renal pathology noted was mesangioproliferative GN followed by membranous nephropathy (MN). IgM with C3 deposits was the most common immunofluorescence pattern observed. Among the patients who had glomerular diseases, complete remission was seen in nine patients, partial remission in 15, and persistent proteinuria in 14. Duration of RA and a high erythrocyte sedimentation rate correlated significantly with persistent proteinuria. Only one patient in the glomerular disease group progressed to dialysis-dependent renal failure. On followup, 11 out of 48 CKD patients showed a significant decrease in estimated glomerular filtration rate and worsened to the next stage of CKD. Renal disease in RA presents with varied renal pathology. MN was seen frequently and was not associated with gold or penicillamine usage. Relatively high incidence of CKD was noted. Hence, it is important to monitor renal function abnormalities periodically in these patients.