Clinical outcomes and survival in AA amyloidosis patients

Amyloid A amyloidosis is a rare complication of chronic inflammatory conditions. Most patients with amyloid A amyloidosis present with nephropathy and it leads to renal failure and death. We studied clinical characteristics and survival in patients with amyloid A amyloidosis.

A total of 81 patients (51 males, 30 females) with renal biopsy proven amyloid A amyloidosis were analyzed retrospectively. The patients were divided into good and poor outcomes groups according to survival results.

Most of the patients (55.6%) had nephrotic range proteinuria at diagnosis. Most frequent underlying disorders were familial Mediterranean fever (21.2%) and rheumatoid arthritis (10.6%) in the good outcome group and malignancy (20%) in the poor outcome group. Only diastolic blood pressure in the good outcome group and phosphorus level in the poor outcome group was higher. Serum creatinine levels increased after treatment in both groups, while proteinuria in the good outcome group decreased. Increase in serum creatinine and decrease in estimated glomerular filtration rate of the poor outcome group were more significant in the good outcome group. At the time of diagnosis 18.5% and 27.2% of all patients had advanced chronic kidney disease (stage 4 and 5, respectively). Median duration of renal survival was 65±3.54 months. Among all patients, 27.1% were started dialysis treatment during the follow-up period and 7.4% of all patients underwent kidney transplantation. Higher levels of systolic blood pressure [hazard ratios 1.03, 95% confidence interval: 1-1.06, p=0.036], serum creatinine (hazard ratios 1.25, 95% confidence interval: 1.07-1.46, p=0.006) and urinary protein excretion (hazard ratios 1.08, 95% confidence interval: 1.01-1.16, p=0.027) were predictors of end-stage renal disease. Median survival of patients with organ involvement was 50.3±16 months.

Our study indicated that familial Mediterranean fever constituted a large proportion of cases and increased number of patients with idiopathic amyloid A amyloidosis. Additionally, it was observed that patient survival was not affected by different etiological causes in amyloid A amyloidosis.