Performance of the modified Systemic Manifestation Score for systemic juvenile idiopathic arthritis in Adult-onset Still’s disease

Objectives To compare the ability of the modified Systemic Manifestation Score (mSMS) and the mPouchot score to distinguish adult-onset Still’s disease (AOSD) with high disease severity in a large cohort. Methods We scored the disease severity of 174 patients and categorized them into high and low disease severity states. The correlation of mSMS and mPouchot score with ESR, CRP, ferritin, liver function tests, and serum cytokines was investigated. Receiver operator characteristic (ROC) curve and logistic regression analysis were performed to compare the ability of mSMS and mPouchot to distinguish patients with severe AOSD. Results Both mSMS and mPouchot score were positively correlated with ESR (both P < 0.001), CRP (both P < 0.0001), and serum ferritin (both P < 0.0001). Moreover, both mSMS and mPouchot score are significantly associated with liver dysfunction and high IL-18 (both P < 0.0001) and IL-6 (both P < 0.01) levels in AOSD patients. Furthermore, the area under curve (AUC) value of mSMS was significantly less than of mPouchot score (0.71 for mSMS, 0.81 for mPouchot score, P < 0.0001). Compared with mPouchot score, mSMS had higher sensitivity (75.64% vs 74.36%) and lower specificity (55.06% vs 76.40%). And mSMS had a worse performance in assessing high disease severity than mPouchot score in logistic analysis. Conclusion Both scores are proven as effective to assess disease severity of AOSD. By contrast, mSMS perform worse in assessing high disease severity of AOSD patients than mPouchot score. Key Points • Both modified Systemic Manifestation Score (mSMS) and modified Pouchot score (mPouchot score) positively correlated with ESR, CRP, and serum ferritin of AOSD patients. • Both scores are significantly associated with impaired liver function and high serum cytokine levels. • mSMS had lower discriminative ability than mPouchot score to distinguish high disease severity of AOSD patients.