The prevalence of subclinical amyloidosis in Polish patients with rheumatoid arthritis

The aims of this study were to determine the proportion of rheumatoid arthritis (RA) patients attending hospital in whom amyloid deposits were present  in abdominal fat aspiration (AFA) samples, and to assess possible risk factors for amyloid development in RA. One -hundred and twenty-one patients (16 males, 105 females) with RA referred to the Department of Rheumatology in Wroclaw  between 1996  and 2001  were studied regardless of RA duration or laboratory findings. Abdominal subcutaneous fine-needle aspiration was performed, and samples of adipose tissue stained with alkaline Congo red then examined by polarized light microscopy. The presence or absence of amyloid fat deposits (AFD) was determined according to whether typical apple-green birefringence was observed. Amyloid deposits were found in 35 (29%) patients. Amyloidosis was significantly more common in males and in patients with longer disease duration. Patients with AFD had previously undergone less treatment with disease-modifying antirheumatic drugs (DMARDs) than those without AFD, and significantly fewer patients with AFD had previously taken methotrexate than those without AFD (25% vs 45%; p<0.01). Renal involvement was found in 12 of 35 patients with AFD (34%). Using the AFA technique, amyloid deposits were found commonly in RA patients, particularly in males with longer disease duration and in patients not treated intensively with DMARDs, especially methotrexate. AFA has potential useful application as a method for detecting amyloidosis before the overt occurrence of renal or other pathology related to amyloid deposits.