To assess the incidence, prevalence, and outcome of amyloidosis associated with inflammatory rheumatic diseases.
An observational study was performed in the outpatient department of Kainuu Central Hospital from 1993 to 2007. The following criteria were used for the performance of abdominal subcutaneous fat aspiration (ASFA) and/or rectal biopsies: erythrocyte sedimentation rate (ESR) > 40 mm/h at two consecutive visits; and proteinuria (> 0.5 g/day) or serum creatinine > 150 μmol/L. Renal biopsy was performed when there was a high suspicion of amyloidosis in cases with negative findings in the above-mentioned biopsies. In addition, amyloid staining was used routinely for mucosal specimens taken in gastroscopy and colonoscopy. The patients were followed until death or to the end of 2007.
New diagnoses of amyloidosis in the consecutive 5-year periods from 1993 onwards numbered 11, 3, and 5, respectively. During the study period, there was a mean annual incidence of amyloidosis of 1.8 [95% confidence interval (CI) 1.1-2.8)/100,000]. At the end of 2007 there were eight subjects with amyloidosis, giving a point prevalence of 12.0/100,000 (95% CI 5.2-23.6). Five patients out of the 19 underwent haemodialysis because of terminal uraemia and three of them also had renal transplantation. Overall, 12 (63%) patients died after a median survival time of 6 (95% CI 4-8) years, one-third from amyloidosis. The 5-year survival rate of the series was 67% (95% CI 41-86).
Amyloidosis is rarely encountered today. ASFA or rectal biopsy facilitates its early diagnosis.