Objective.: To evaluate the clinical significance of the 2016 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR)/Pediatric Rheumatology International Trials Organization (PRINTO) classification criteria for macrophage activation syndrome (MAS) in patients with adult-onset Still disease (AOSD).Methods.: We performed a retrospective analysis of patients with AOSD with fever who were admitted to Severance Hospital between 2005 and 2016. The patients with AOSD were evaluated for MAS using the 2016 classification criteria for MAS. Clinical features, laboratory findings, and overall survival were analyzed. Logistic regression analysis was used to evaluate the factors associated with in-hospital mortality.Results.: Among 64 patients with AOSD, 36 (56.3%) were classified as having MAS. The overall survival rate was significantly lower in patients with MAS than in those without (67% vs 100%, p < 0.001). Multivariate analysis showed that a low erythrocyte sedimentation rate, a low albumin level, an increase in ferritin of over 2 folds, and the development of MAS on admission were significantly associated with mortality in patients with AOSD.Conclusion.: The 2016 EULAR/ACR/PRINTO classification criteria for MAS are potentially useful for the identification of patients with AOSD at high risk for a poor outcome. Febrile patients with AOSD should be monitored with the 2016 classification criteria for MAS in the early diagnosis and proper treatment of MAS.

Neutrophil to lymphocyte ratio (NLR) was introduced to predict poor prognosis in various diseases, but not all variants of ANCA-associated vasculitis (AAV). In this study, we aimed to investigate whether NLR at diagnosis can estimate vasculitis activity at diagnosis and poor prognosis during follow-up in patients with AAV. We retrospectively reviewed the medical records of 160 patients with AAV. We collected clinical and laboratory data at diagnosis and obtained remission and death as poor prognosis. We stratified AAV patients into three groups according to tertile and defined the lower limit of each highest tertile as the optimal cut-off (5.9 for NLR and 15.0 of Birmingham vasculitis activity score [BVAS] for severe AAV). The mean age at diagnosis was 55.2 years and 48 patients were men. In the univariable linear regression analysis, BVAS was negatively correlated with lymphocyte count and positively correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and NLR. In the multivariable linear regression analyses of ESR and CRP with either lymphocyte count or NLR, lymphocyte count (β = − 0.160) and NLR (β = 0.169) were associated with BVAS. Patients having NLR ≥ 5.9 exhibited severe AAV more frequently than those having NLR < 5.9 at diagnosis (relative 2.189, P = 0.023). Patients having NLR ≥ 5.9 exhibited a higher frequency of AAV relapse, but not death, than those having NLR < 5.9 (P = 0.016). NLR at diagnosis can estimate vasculitis activity at diagnosis and predict relapse during follow-up in patients with AAV.