Remission of proteinuria and preservation of renal function in patients with renal AA amyloidosis secondary to rheumatoid arthritis

Renal AA amyloidosis presents as a life-threatening disease in patients with rheumatoid arthritis (RA). Although several newly developed immunosuppressive drugs have been tried, patients often progress to end-stage renal failure with unsatisfactory survival rate. A total of nine consecutive cases of severe nephrotic renal AA amyloidosis presented to us. Complete remission of proteinuria was observed in four cases (responders), and the remaining five reached the end point of haemodialysis or death (non-responders); these groups were retrospectively compared. The patients were treated with immunosuppressants, biological drugs and anti-hypertensive drugs. Levels of serum creatinine (S-Cr), urinary protein-creatinine ratio (UP/UCr), blood pressure (BP) and C-reactive protein (CRP) were measured. Histological characteristics of renal amyloid deposition and extent of kidney injury were also scored. Prior to treatment, clinical data (S-Cr, UP/UCr, BP and CRP) and histological severity (glomerular sclerosis, tubulointerstitial injury and extent of amyloid deposition) observed in the renal biopsy specimen were not significantly different between the groups. Following therapeutic intervention, proteinuria disappeared (UP/UCr < 0.3) in responders within 12 +/- 5.4 months but persisted in non-responders. Consequently, renal function stabilized in responders, but it deteriorated in all non-responders. Strict inflammatory control along with optimal control of hypertension was achieved in responders during the treatment. Regardless of histological severity, intensive therapeutic intervention that includes strict inflammatory control and optimal control of hypertension may change the histology-predicted prognosis of RA-associated renal AA amyloidosis.