Renal involvement in AA amyloidosis: clinical outcomes and survival

The natural history of AA amyloidosis is typically progressive, leading to multiple organ failure and death. We analyzed the etiology as well as clinical and laboratory features of patients with biopsy-proven AA amyloidosis and evaluated the ultimate outcome.

Seventy-three patients (24 female; mean age 41.85±15.89 years) were analyzed retrospectively. Demographic, clinical and laboratory features were studied and the outcome was assessed.

Familial Mediterranean Fever and tuberculosis were the most frequent causes of amyloidosis. Mean serum creatinine and proteinuria at diagnosis were 4.65±4.89 mg/dl and 8.04±6.09 g/day, respectively; and stage I, II, III, IV and V renal disease were present in 19.2%, 13.7%, 16.4%, 11%, and 39.7% of the patients, respectively. ESRD developed in 16 patients during the follow-up period. All of the ESRD patients started a dialysis programme. Thirty patients (41%) died during the follow-up period; median patient survival was 35.9±6.12 months. Old age, tuberculosis etiology, advanced renal disease and low serum albumin levels were associated with a worse prognosis. Serum albumin was a predictor of mortality in logistic regression analysis.

The ultimate outcome of the patients with AA amyloidosis is poor, possibly due to the late referral to the nephrology clinics. Early referral may be helpful to improve prognosis.