Renal function at the time of renal biopsy as a predictor of prognosis in patients with primary AL-type amyloidosis

Abstract

Background

Amyloid light-chain (AL)-type amyloidosis is a plasma cell disorder with a poor prognosis for survival. Although prognostic factors, such as the number of organs involved and heart function or failure in respond to therapy have been clarified based on studies including a large series of patients, there are large interindividual differences in the prognosis of patients with primary AL-type renal amyloidosis.

Methods

To clarify the prognostic factors of AL-type renal amyloidosis, we retrospectively investigated the clinical manifestations, histopathological data, and prognosis of 21 patients with amyloidosis, who had been diagnosed by renal biopsy.

Results

Eleven patients died, at a mean observational time of 21.7 months after renal biopsy, whereas the mean observational time was 51.0 months for the 10 patients who survived. The creatinine clearance rate was significantly higher, and the serum creatinine concentration and the grade of interstitial damage were significantly lower in surviving patients (P < 0.05). The presence of amyloid fibrils in organs other than the kidney did not influence prognosis for survival. However, the intraventricular septum was thinner in surviving patients (P < 0.1). Thirteen patients had undergone melphalan-prednisolone therapy, but it did not affect prognosis for survival. Cox proportional hazard regression analysis revealed that the renal function at the time of diagnosis was a significant and independent prognostic factor for survival.

Conclusions

Our study demonstrated that renal function at the time of biopsy and renal interstitial damage are the best predictors of survival in AL-type renal amyloidosis.