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.


CONCLUSIONS
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.
Evensen
K J
KJ
Department of Rheumatology, Institute of Clinical Medicine, University of Tromsø, Norway.
Swaak
T J G
TJ
Nossent
J C
JC
D000328:Adult; D015415:Biomarkers; D002097:C-Reactive Protein / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D005293:Ferritins / Q000097:blood* / Q000276:immunology; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation / Q000276:immunology; D008297:Male; D008875:Middle Aged; D016706:Still's Disease, Adult-Onset / Q000097:blood* / Q000175:diagnosis
D015415:Biomarkers; D002097:C-Reactive Protein; D005293:Ferritins