Objective: To investigate whether administration of low dose cyclosporine for 2 years induces structural changes in the kidneys of patients with rheumatoid arthritis (RA).
Methods: Renal biopsies were performed in 11 patients with RA who had been treated with cyclosporine [mean dose 3.3 mg/kg/day; mean maximum dose 4.4 (3.5-5.1) mg/kg/day; mean cumulative dose 2.8 (1.6-3.9) g/kg] [mean (range)] for a mean period of 26 (15-30) months. The renal biopsy specimens and specimens of autopsy material of 22 control patients with RA matched for age, disease duration, sex, and previous use of gold and/or D-penicillamine were scored by 2 renal pathologists according to a semiquantitative scoring system (absence of lesions to severe lesions).
Results: In the patients taking cyclosporine, creatinine clearance decreased from 111 ml/min before cyclosporine to 82 ml/min (-26%) after 24 months. Seven percent of the glomeruli in the renal biopsy specimens compared to 13% of glomeruli in the autopsy specimens showed obsolescence. Minimal arteriolopathy (one hyaline deposition in one arteriole) was detected in 3 biopsy specimens and in one autopsy specimen. Moderate and severe lesions were not seen. Tubular atrophy was common but mild in both the biopsy specimens (10/11 patients) and the autopsy specimens (16/22 patients). Five of 11 renal biopsy specimens and 13 of 22 autopsy specimens showed minimal to slight interstitial fibrosis. All biopsy specimens were classified as Group I (minimal lesions) according to the advisory board of nephropathologists.
Conclusion: Longterm continuous treatment of RA with low dose cyclosporine does not result in more structural nephropathy than the disease process itself, in spite of substantial and persistent deterioration of the renal function.