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.