Increased ferritin response in adult Still's disease: specificity and relationship to outcome.

BACKGROUND: The disproportionate ferritin response encountered in some patients with adult Still's disease (ASD) may reflect a fundamental aspect in the pathophysiology of ASD. METHODS: An observational case-control study of 22 ASD patients followed for 63 months. Baseline laboratory data were compared with age- and gender-matched controls with new-onset rheumatoid arthritis (RA). Serum levels of ferritin and C-reactive protein (CRP) and the ferritin/CRP ratio were related to clinical outcome in ASD through nonparametric statistical analyses. RESULTS: Compared to RA patients, haemoglobin levels were lower (11.8 vs. 13.5 g/dL; p = 0.009) and leucocyte counts (17.1 vs. 8.6 10(9)/mL; p<0.001), erythrocyte sedimentation rate (ESR) (84 vs. 38 mm; p = 0.001), CRP (154 vs. 27 mg/L; p<0.001), aspartate aminotransferase (ASAT) (52 vs. 23 U/l; p = 0.004), serum ferritin (8750 vs. 62 microg/L; p<0.001) and ferritin/CRP ratios (9.7 vs. 1.7; p<0.001) were higher in ASD patients at baseline. Six patients (27%) achieved sustained remission (monocyclic disease), while 16 patients (73%) developed chronic disease (progressive in 27%, relapsing/remitting in 46%). The levels of ESR and CRP or other baseline variables were not associated with outcome. However, baseline serum ferritin was significantly higher in ASD patients with chronic disease (p = 0.04), while a cut-off of five times the normal upper level (NUL) was 100% sensitive and 60% specific for predicting chronic disease. CONCLUSION: An exaggerated ferritin response with levels>5 times the NUL and high ferritin/CRP ratios is useful for distinguishing between ASD and RA patients. Ferritin levels>5 times the NUL are also associated with a chronic disease course.

Epidemiology and outcome of adult-onset Still's disease in Northern Norway.

BACKGROUND: Adult-onset Still's disease (AOSD) is considered a rare disease, but few data exist on the incidence and prevalence of AOSD. This study has analysed the epidemiology, disease presentation, and outcome of AOSD in a stable homogeneous population in Northern Norway. METHODS: A retrospective cohort study of all AOSD patients registered in 1990-2000 at the only hospital in the region with a Rheumatology Service. Clinical diagnosis and exclusion of patients were directed by the Yamaguchi criteria for AOSD. Demographic and clinical data at baseline were extracted from patient records and supplemented with data gathered at control visits. Data were analysed with nonparametric methods. RESULTS: AOSD was ascertained in 13 patients; the estimated annual AOSD incidence was 0.4/100,000 adults (95% CI 0.11-0.97), while point prevalence of AOSD increased from 3.4/100,000 (95% CI 0.8-9.4) in 1990 to 6.9/100,000 in 2000 (95% CI 2.7-14.2). Mean diagnostic delay was 5.2 months (range 0.5-18). Serum ferritin > 5 times the normal upper level had 63% diagnostic sensitivity. During 69 months' follow-up, one patient died, 6/13 patients achieved sustained remission, while six patients developed a chronic progressive (n = 3) or a relapsing/remitting disease course (n = 3). Four of these six patents had to enter social security programmes. CONCLUSION: The annual incidence of AOSD in Northern Norway is at least 0.4/100,000 adults. AOSD in this region is more prevalent than in France or Japan, affects more males, and approximates to the prevalence of juvenile Still's disease. Half of all patients have a monocyclic disease course, while mortality and invalidity occur in patients with chronic disease.