#2282 Outcomes of renal amyloidosis: 8 years experience of tertiary center

Amyloidosis is a disease caused by the extracellular deposition of amyloid material that leads to organ dysfunction. Renal involvement is frequent and is characterized by amyloid fibrils pathologic deposition in glomeruli, vessels and interstitium. The most common presentation is nephrotic-range proteinuria or nephrotic syndrome and can progress to end stage kidney disease (ESKD). Prognosis is usually poor, especially with cardiac and severe renal involvement that requires renal replacement therapy. The goal of this study was to analyse the outcomes of patients with amyloidosis followed at the nephrology clinic in our centre.

Descriptive analysis of all confirmed amyloid patients, followed by the Nephrology department from January 2015 to June 2023.

We identified 49 patients with a mean age of 64 ± 16 years [18-88], mainly Caucasian (n = 47, 82%) and male (n = 28, 57%). The majority of patients were diagnosed through renal biopsy (26, 53%). The most common amyloid type was AL (n = 18, 38%), followed by ATTR (n = 16, 33%) and AA (n = 12, 25%). In 3 patients the amyloid type couldn't be characterized. Renal presentation was mostly as CKD 28/49 (57%), 15/49 (30.6%) as nephrotic syndrome and 6/49 (12%) patients as AKI. At presentation, almost half of the patients (24/49, 49%) had nephrotic-range proteinuria, with a mean proteinuria of 6.72 ± 6.12 g/d [0.103-19.8] and mean sCr was 2.6 ± 3.1 mg/dl [0.5-18.9].

AL amyloidosis had an almost equal distribution between lambda (9/18, 50%) and kappa chain (8/18, 44%, one unknown). Extrarenal involvement was frequent, mainly cardiac (12/18, 67%). Also 12/18 (67%) patients needed dialysis after a mean of 9 ± 15 months post-diagnosis, 16/18 (89%) received treatment and mortality was 61%, in mean 16 ± 17 months post-diagnosis, mainly due to disease progression.

AA amyloidosis was secondary to chronic infection in 7/12 (58%), 3/12 (25%) autoimmune diseases and in 2/12 (17%) unknown. Extrarenal involvement was less frequent, also mainly cardiac (3/12, 25%). 7/12 (58%) patients needed dialysis after a mean of 97 ± 117 months post-diagnosis and mortality was 58%, in mean 46 ± 66 months post-diagnosis, mainly due to acute infection. Two patients were diagnosed already on dialysis.

Regarding ATTR amyloidosis, all patients had a positive genetic test, extrarenal involvement was very frequent (13/16, 81%), mostly cardiac and peripheric nervous system. No patients required dialysis during follow-up, and one patient died of unknown cause.

In our cohort, renal AL and AA amyloidosis had poor prognosis, with a high progression to ESKD and very significant mortality, irrespective of treatment. Conversely, ATTR amyloidosis patients had lower progression to dialysis and death, probably as a consequence of disease-modifying therapies instituted in recent years.