Background Rheumatoid arthritis (RA) is a chronic, recurrent autoimmune inflammatory disease, which may be complicated, like other chronic inflammatory diseases, by systemic secondary (reactive) AA amyloidosis (AAa). The precursors of AA amyloid protein fibrils are produced by the liver. During the progressive, cumulative process of systemic AAa the serum amyloid A proteins spread via the blood-stream and deposit throughout the body. AAa in its early stage involves only a few tissue structures (blood vessels, collagen, and reticulin fibres, basal membranes, etc.) in some organs, and increasingly more in its later stages. In advanced stages of AAa massive amyloid deposits in the kidney lead to renal insufficiency and the patients die of uremia. The extension and quantity of amyloid deposits depend on the production, and/or elimination (resolution, excretion) of amyloid proteins, or from the pathologist’s point of view on the stage of this progressive disease at death.
Objectives The aim of this study was to determine the influence of age, sex, onset of RA, and disease duration on amyloidosis.
Methods A randomised autopsy population of 161 in-patients (female 116, average age of 64.9 years; male 45, average age of 66.2 years at death) with rheumatoid arthritis (RA) was studied.
The existence of amyloidosis and extent of amyloid deposits at death was determined histologically.
The average amount of amyloid deposition in various structures was visually evaluated on a 0 to 4 plus scale.
The correlations were determined by Mann-Whitney (Wilcoxon), critical random check, Student (Welch) t-probe, and by c²-tests, comparing the age, sex, onset of RA, and duration of disease at the time of death: with or without amyloidosis, mild (? <2? per patient) and severe amyloidosis (?2
Results Systemic secondary (AA) amyloidosis was observed in 34 (21.1%) of 161 cases: in 21 cases amyloidosis was, and 13 it was severe. There was no significant difference of survival time (age at death), onset of RA, and disease duration between males and females, or between patients with and without amyloidosis. RA started earlier, the disease duration was longer, and the age of the patients at death was significantly lower (p < 0.005) in cases with severe amyloidosis, in comparison to those with mild amyloidosis.
Conclusion Amyloidosis may develop in both sexes, and may start at any time during RA. AAa existed in different stages (mild: characterised by sporadic and minimal amyloid deposits, or severe: characterised by diffuse and massive amyloid deposits) at the time of death. There were no significant differences in disease duration and survival time between males and females, or between patients with and without amyloidosis, suggesting that amyloid deposition may occur at different rates. AAa may develop as a rapidly progressive, or as a chronic, slowly progressive disease. Possibly, the process may become inactive (quiescent), or even regress at some point in time.
The risk of severe amyloidosis (2 <) is higher in patients with early onset and with long duration of RA, and in these patients the age at death is significantly lower (p < 0.005).