Clinical features and hyperferritinemia diagnostic cutoff points for AOSD based on ROC curve: a Chinese experience

Hyperferritinemia has been reported in adult-onset Still's disease (AOSD). This study aims to investigate clinical features of AOSD in Chinese population and diagnostic value of different hyperferritinemia cutoff points based on ROC curve. A total of 48 patients from October 2002 to February 2007 diagnosed AOSD in the department of rheumatology, the first affiliated hospital of Sun Yat-set University were enrolled. A total of 86 patients mainly complaining fever >39°C for over one week and meeting Yamaguchi criteria but confirmed as non-AOSD by other serological or pathological tests were obtained from the same department as controls. Total serum ferritin levels were determined at the time of admission. Clinical features of AOSD in Chinese population were similar to previous studies. Significantly higher levels of total serum ferritin were presented in patients with AOSD (8100.7 ± 13678.5) compared with non-AOSD controls (448.3 ± 539.4) (P < 0.01). No differences were found in serum ferritin level between different categories of non-AOSD patients (P > 0.05). High value of area under receiver operating characteristic curve (ROC curve) suggested that ferritin was very predictive in AOSD diagnosis. Three cutoff points were picked based on clinical practice and ROC curve. Ferritin level ≥2,500 µg/L appeared to be highly specific for a diagnosis of AOSD, yet the low sensitivity may falsely ruled out patients with true AOSD. Hyperferritinemia ≥750 µg/L was seldom observed in inflammatory diseases or solid tumor. Hyperferritinemia ≥1,250 µg/L could mostly rule out other autoimmune diseases and hematologic diseases. Combined Yamaguchi criteria and hyperferritinemia gave better prediction for AOSD. In conclusion, different hyperferritinemia cutoff points observed in ROC curve help to optimize diagnostic and therapeutic strategy.