Objective: To determine the outcome of amyloidosis associated with juvenile idiopathic arthritis (JIA) in a hospital-based series.
Methods: Patient registers and amyloidosis biopsy files of the Department of Pediatrics of Rheumatism Foundation Hospital, the main tertiary center for inflammatory joint disorders in children in Finland, were scrutinized from 1976 to the end of 2003 to look for amyloidosis in patients under age 19 years. Medical records were reviewed and patients were interviewed by telephone. The causes of any deaths were obtained from death certificates.
Results: Twenty-four patients under age 19 years with biopsy-proven amyloidosis were found. As a sign of renal disease at the time of diagnosis of amyloidosis, 16 patients (67%) had proteinuria, but none had renal insufficiency. The 5-year survival rate of the series was 87.5% (95% CI 75% to 100%), and 10-year survival was 75% (54% to 92%). Ten patients (42%) out of the 24 died during a mean followup of 15.4 (range 1.5-27.6) years. The main cause of death was related to JIA in all patients but one. Patients treated with prednisolone alone from the diagnosis of amyloidosis onward had a mortality rate significantly higher than those taking disease modifying antirheumatic drugs and/or cytostatics (p = 0.001). At the end of followup, 14 patients (58%) were alive, 12 with normal renal function (3 of them had undergone renal transplantation), one had renal insufficiency, and one proteinuria. Proteinuria disappeared in 4 patients who were proteinuric (2 with nephrotic syndrome) at baseline, and their renal function remained normal. All the live patients had completed at least the 9 years of compulsory education, and 4 had academic degrees. Two female patients had delivered healthy children.
Conclusion: The outcome of JIA-associated amyloidosis is poor. However, renal disease regressed in some patients under vigorous treatment. Successful treatment makes an active life possible for these patients.