Prognostic factors for renal amyloidosis: a clinicopathological study using cluster analysis.

Objective: There is no standardized therapy for renal amyloidosis, which shows rapid progression and poor prognosis. Here, we used cluster analysis to examine the correlation between amyloid-related renal damage and prognosis, and determined the clinicopathological prognostic factors for renal amyloidosis.

Methods And Patients: We analyzed 125 patients with renal amyloidosis (men/women: 43/82; mean age at renal biopsy: 58.8+/-11.1 years, +/-SD; range: 21-78 years). Cluster analysis was performed using clinical parameters, renal histological findings, type of renal amyloidosis, and follow-up data. We also analyzed survival data.

Results: We divided 125 cases (prognosis was checked in 97 [77.6%] cases) into three groups by cluster analysis. In the cluster groups, accelerated progression correlated with serum creatinine (s-Cr) levels at renal biopsy and histological grade of renal damage by amyloid deposition (p<0.0001). The most important prognostic factors were glomerular, tubulointerstitial, and vascular lesions induced by amyloid deposition at biopsy (p<0.0001). We also found that amyloid-A (AA) type amyloidosis correlated is more significantly with amyloid-mediated vascular (P=0.0010) and tubulointerstitial lesions (p=0.0705) than with amyloid-L (AL) type amyloidosis. Proteinuria and nephrotic syndrome were more severe in AL than AA amyloidosis (p=0.0836). The 10-year individual survival rate was about 20%, and most deaths were due to cardiovascular disease and infection.

Conclusion: Our results indicate that the quantity of amyloid deposition in the kidney, and the extent of glomerular, tubulointerstitial, and vascular damage are significant renal prognostic factors in amyloidosis.