THU0553 THE IMPACT OF BACKGROUND BIOLOGICAL THERAPY ON SYSTEMIC JUVENILE IDIOPATHIC ARTHRITIS-ASSOCIATED MACROPHAGE ACTIVATION SYNDROME: A SINGLE CENTER STUDY
Authors: Riccardo Russo, Maria Katsikas
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Macrophage activation syndrome (MAS) is a severe complication of Systemic juvenile idiopathic arthritis (SJIA). Biological therapy of SJIA may modify the clinical expression of MAS (1). Objectives: to assess and compare the clinical, biochemical. and haematological features of SJIA-associated MAS in patients treated with biologic (B) or non-biologic (NB) agents. Methods: retrospective analysis of data from dedicated medical records and databases. Inclusion criteria included: diagnosis of SJIA according to the ILAR criteria, diagnosis of MAS according to the expert's opinion, and prescription of corresponding therapy. Patients were followed and treated at a tertiary center from 2006 to 2018. Demographical, clinical, haematological, biochemical and treatment-related features were recorded. The worst recorded values (e.g. highest ferritin levels) during each MAS episode were included for analysis. Outcomes (complete or partial recovery, death) and fulfillment of current classification criteria (2) were also recorded. Comparisons between groups (patients developing MAS during B therapy vs. NB therapy) were performed by chi square or Wilcoxon rank sum tests. <h3>Results</h3> Twenty-four (14 F, 10 M) patients who developed 31 MAS episodes were included. Age at SJIA onset 4 years, age at MAS onset 6 years; 10 episodes occurred during the initial (0-3 months) stage of SJIA course. Patients were receiving biological agents (canakinumab 4, tocilizumab 4, anakinra 1, etanercept 1) in 10 (32%) MAS episodes. Frequency of cardinal clinical features was similar in both groups. During MAS course, ferritin (1,408 vs 26,574 ng/ml, p &lt; 0.001), LDH (922 vs 3308 IU/L, p = 0.04), SGOT (66.5 vs 389 IU/L, p = 0.02), and triglycerides levels (259 vs 352 IU/L, p = 0.03) were lower in B than in NB treated patients, while platelet count (215 vs 66 n/μl, p &lt; 0.01), and hemoglobin (104 vs 79 g/dL, p &lt; 0.01) were higher in the B than in the NB treated patients. No significant differences were found in GGT, fibrinogen, SGPT levels or neutrophil count. Duration of admission during MAS tended to be longer in the NB treated group (31 days) than in the B group (16 days). Treatment of MAS included high dose steroids, cyclosprin, and/or biological agents. Five patients, all belonging to the B group (p &lt; 0.001), did not fulfill current SJIA-MAS classification criteria. There were 4 deaths recorded, all belonging to the NB group. <h3>Conclusion</h3> SJIA patients treated with biological agents exhibit similar clinical features than those treated with non-biologic therapy. However, different haematological and biochemical variables are significantly milder in patients on biological therapy, which may limit the utility of classification criteria in this group. Assessment of these findings in larger cohorts is needed. <h3>References</h3> [1] Schulert GS, et al. Effect of Biologic Therapy on Clinical and Laboratory Features of Macrophage Activation Syndrome Associated With Systemic Juvenile Idiopathic Arthritis. Arthritis Care Res 2018;70:409-19. 2. Ravelli A, et al. 2016Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation Collaborative Initiative. Ann Rheum Dis2016;75:481-9. <h3>Disclosure of Interests</h3> Riccardo Russo Speakers bureau: Novartis, Abbvie, Maria Katsikas: None declared