Background (SV), secondary AA amyloidosis (AAa), lethal septic infection (SI) with or without purulent arthritis (PA) are major complications of rheumatoid arthritis (RA). The co-existent complications may influence their prevalence and may modify their clinical characteristics (symptoms).
Objectives The aim of this study was to determine: the influence of coexistent major complications (SV and AAa) of RA in the mortality due to lethal SI (with or without PA).
Methods A randomized (non-selected) autopsy population of 161 in-patients with RA was studied. RA was confirmed clinically according to the criteria of ACR. Lethal SI, with or without PA, SV, AAa was histologically diagnosed post mortem. Amyloid A deposits were demonstrated by Congo red staining. The links between lethal SI (with or without PA) and coexisting complications (SV, AAa) were analysed by c2-test.
Results Lethal SI was found in 24 (14.91%) of 161 RA patients. Lethal SI was accompanied by PA in 12 (50 rel%) of 24 patients. PA did not complicate RA without lethal SI.
SV was observed in 36 (22.36%) of 161 RA patients. Vasculitis was associated with lethal SI in 3, PA in 1 of 36 patients.
AAa complicated RA in 34 (21.1%) of 161 cases. Amyloidosis was associated with lethal SI in 3, PA in none of 34 patients.
There was a significant correlation between lethal SI and PA (association coefficient: 1, c2=66.9456, p<0.0000).
There was no significant correlation between lethal septic infection (with or without PA) and vasculitis, or amyloidosis.
Conclusions Maximal association coefficient: 1 of lethal SI and PA refers to a very close connection between lethal SI and suppurative arthritis; SI may be caused or complicated by PA. After intraarticular intervention lethal SI should be regarded as a consequence of a primary PA. In RA active inflammation of the joints represents a favorable target (locus minoris resistentiae) for secondary bacterial inflammation. In these latter cases (without former intraarticular intervention) PA may be regarded as the complication of general SI.
The negative value of association's coefficient and not significant relationship between lethal SI and SI without PA supports the view that SI without PA may be considered as a severe indirect consequence of RA caused by any bacteriemia, mostly in elderly patients with weak immune response, in many cases treated with steroids and/or immunosuppressive drugs.
SV, or AAa did not influence the prevalence of lethal SI (with or without PA). The negative value of association's coefficient indicates that SV, AAa and SI (with or without PA) are independent complications of RA. SV – according to our interpretation – is the basic pathological process in RA, caused by circulating various immuncomplexes.
AAa may be regarded as a direct consequence of increased serum amyloid A production in the liver, due to chronic inflammation of RA.
Disclosure of Interest : None declared