E26 Macrophage activation syndrome in systemic juvenile idiopathic arthritis, one centre experience
Authors: Hashad Soad S , Etayari Hala M , Almsellati Iman A , Etfil Majda N , Altwati Aya , Awhida Zuhaira 
Published: August 2023

Abstract

Background
Macrophage Activation Syndrome (MAS) in Systemic Juvenile Idiopathic Arthritis (SoJIA) is a potentially life-threatening condition. The prevalence of MAS in SoJIA population is estimated to be 10%. However, reports suggested that the number of SoJIA patients with subclinical MAS may be as high as 40%. Early recognition of MAS is crucial because timely treatment is important for survival.

Objective
To describe the clinical and laboratory features of patients with MAS associated with SoJIA

Methods
Data from cohort of 38 SoJIA patients with and without MAS from January 2006 to January 2020 were included and retrospectively reviewed. Data were collected on demography, clinical/laboratory features and treatment.

Results
There were 38 patients with SoJIA diagnosed according to the International League Against Rheumatism (ILAR) criteria. 47.4% of them were males and 52.6% were females. They were followed up for a period of 6.3 ± 4.4 years. The mean period from appearance of symptoms to first follow up in rheumatology clinic was 5 ± 6 months. The disease course was monocyclic in 39.5%, polycyclic in 28.9% and persistent in 31.6% of the patients.
Of the total cohort, 10% of the patients were classified as having MAS, half of them presented with MAS at diagnosis and the rest developed MAS during the disease course. Only One patient experienced recurrent MAS (3 times). Male to female ratio is 3:1. The mean age at diagnosis was 8 ± 6 years.
Skin rash was the most presenting feature in the two groups. Hepatosplenomegaly and serositis were most common in sJIA with MAS patients.
In comparison to SoJIA patients without MAS, all patients have thrombocytopenia, leukopenias, with mean ferritin level of 1668 in MAS patient and 947 in non-MAS group. The obligate criteria for the diagnosis of MAS according to the 2016 MAS classification criteria are increased ferritin &gt;684 μg/l, elevated lactate dehydrogenase (LDH) and Glutamic Oxaloacetic Transaminase (GOT). All patients have a declining ESR and high CRP and all patients were anaemic. Bone marrow biopsy was done in 50% of the patients. In SoJIA without MAS, ESR mean level was 94 (±38.5) mm/h, CRP mean level of 62 (± 65.8) mg/dl and platelets count mean level of 561 (±215) × 109/l.

Treatment
all MAS-SoJIA patients were treated with IV methylprednisolone and IVIG compared with 50% of non-MAS-SoJIA patients. In the MAS group, dose of oral prednisolone was (1–2 mg/kg/day) while in non-MAS group was (0.5–1 mg/kg/day). A patient developed MAS twice while on the 7th dose of anakinra and the third MAS on the 6th dose of tocilizumab. Ciclosporin (3 mg per/kg/day) was the treatment of choice for him.

Conclusions
In our series, prevalence of MAS was 10% which mainly affect the male which is the same as the estimated prevalence of MAS worldwide. Arthritis occurred less frequent in MAS group cases in comparison to hepatosplenomegaly which was more common among MAS group. Rash and serositis were the most common extra-articular manifestations. The main treatment modality was steroid in all of the patients. All the MAS patients were successfully treated with high dose of IVIG, methylprednisolone and ciclosporin, including the patients who developed MAS while on biologics.

Ethics
Our study was approved by local ethical committee of pediatric department at Tripoli children hospital.