[Secondary amyloidosis complicated rheumatoid arthritis, prevalence study in Italian population]

Amyloidosis refers to the extracellular deposition of proteinaceous insoluble fibrils in various tissues, resulting in organ compromise. The most common form of amyloidosis occurs secondary to chronic inflammatory disease, in which AA fibrils, derived from the acute phase protein, serum amyloid-A (SAA). We evaluated the prevalence of AA with lip biopsy on 106 rheumatoid arthritis patients (according to 1988 ARA criteria), asymptomaticwith regard to amyloidosis (90 females, 16 males). On histological salivary gland samples we evaluated the presence of AA by an immunohistochemical method [Anti Human Amiloid clone MC-1 (DAKO, Italy)]. We observed a positivity of AA on 8/106 patients (5 F/3 M) 7.54%. When the total data were divided into three groups considering the different lenght of the disease (number of years) we observed the following prevalence data: group A, years of disease < 3, 2/45, 4.44% (F 1/M 1), group B, years of disease 3-5, 2/26, 7.69% (F 1/M 1), group C, years of disease > 5, 4/35, 11.42%. The statistical analysis showed a significative difference between group A and B (p < 0.025), between group B and C (p < 0.025) and between group A and C (p < 0.01). The 8 patients with AA positivity showed also an high disease activity in comparison with 98 negative patients: DAS 5.62 +/- 0.48 vs 4.36 +/- 0.79, DAS28 5.84 +/- 0.76 vs 4.48 +/- 0.87 (p < 0.05). Our data showed that secondary AA amyloidosis prevalence in asymptomatic Italian rheumatoid arthritis patients was 7.54%; moreover this complication was present in 4.44% of early rheumatoid arthritis patients.