What is the prognosis of AA (inflammatory) amyloidosis?

Updated: Jan 08, 2021
  • Author: Jefferson R Roberts, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

The prognosis of the AA amyloidosis, regardless of the prognosis of the primary disease, has generally been associated with the degree of renal compromise present at the time of diagnosis, ie, poor prognosis is associated with a serum creatinine level greater than 2 mg/dL or a serum albumin level of less than 2.5 g/dL. Mean survival is 2-3 years. 

Patients with access to renal replacement therapy have improved survival to more than 4 years. In the latter cases, infection was the major cause of death. [27] With improved aggressive anti-infectious treatment, further enhanced survival likely is possible, even without specific treatment that allows resorption of the deposited fibrils or inhibits further deposition.

In some cases, usually of infectious origin, the clinical consequences of amyloid deposition may dissipate with reduction or disappearance of the tissue deposits if the inflammatory disease can be suppressed totally or eliminated. If treatment of the primary disease is unsuccessful, death of organ failure secondary to the amyloid deposition is the rule. The progression of amyloidosis is related to the production and concentration of the circulating amyloidogenic precursor protein. The concentration of the acute phase protein SAA during follow-up correlates with deterioration of renal function, amyloid burden, and mortality in AA amyloidosis.

In a study of 374 patients with AA amyloidosis who were followed for 15 years, the median survival after diagnosis of amyloidosis in those with a sustained acute phase response was 133 months. As per this study, the risk of death was 17.7 times as high among patients with SAA concentrations in the highest eighth, or octile, (≥155 mg/L) as among those with concentrations in the lowest octile (< 4 mg/L). [28]

In general, amyloidosis shortened the median life span 7.7 years, and survival strongly depended on controlling the underlying inflammatory process. Amyloid deposits regressed in 60% of patients who had a median SAA concentration of less than 10 mg/L, and survival among these patients was superior to survival among those in whom amyloid deposits did not regress. Sustained increased concentration of SAA is the most significant risk factor in AA amyloidosis, whereas reduction of SAA concentration improves survival and is associated with arrest or even regression of amyloid deposits. [13, 29, 30]

As per the Finnish Registry for Kidney Diseases, 502 patients with amyloidosis were identified entering RRT from 1987-2002. Eighty percent of these patients had amyloidosis associated with an underlying rheumatic disease. The 5-year survival rates among patients with the RA, AS, and juvenile idiopathic arthritis were 18%, 30%, and 27%, respectively. [31]

Cardiac amyloidosis appears to be a predictor of worse outcome with a 5-year survival of 31% versus 63% for patients without cardiac involvement in a retrospective series of 42 patients from Japan. [32]

The degree of renal involvement is important, with patients who have elevated creatinine levels doing worse compared with patients with a normal creatinine. The pattern of renal involvement is also important. Specifically, glomerular involvement with amyloid and fibrosis appear to have clinical course characterized by deteriorating renal function compared to patients with other types of renal involvement. Generally, however the median survival is over 5 years. [34]


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