Ten times higher than general rate
Nearly 10% of children with systemic lupus erythematosus (SLE) developed macrophage activation syndrome (MAS) at some point during a mean follow-up time of more than 3 years at one center, and most were concomitantly diagnosed with the syndrome.
Although the investigators from the University of Toronto reported significantly higher mortality among patients with MAS, most cases were successfully treated with corticosteroids, and no relapses were observed during follow-up.
MAS was first identified in patients with juvenile idiopathic arthritis and is most well known as a complication of that broadly named disease, but data on outcomes and disease course in SLE patients are limited, first author Roberto Ezequiel Borgia, MD, and his colleagues wrote in their report in Arthritis & Rheumatology.
The researchers identified 403 children with SLE seen at the Hospital for Sick Children in Toronto during 2002-2012. Overall, 38 patients (9%) had MAS; of those patients, 68% received a MAS diagnosis within 7 days of the SLE diagnosis – termed “concomitant” diagnosis – while another 29% received a MAS diagnosis within 180 days of their SLE diagnosis.
The researchers explained that “since there are no validated nor universally accepted diagnostic criteria for MAS in SLE, the definition of MAS was based on the treating pediatric rheumatologist’s expert opinion at the time of the initial presentation.” The most common presenting feature of MAS was fever (100%), followed by generalized lymphadenopathy (24%), hepatomegaly (18%), CNS dysfunction secondary to MAS (18%), hemorrhage (13%), and splenomegaly (10%).
The average age of the children at diagnosis was nearly 14 years, and 79% were female. The average follow-up was 3.5 years. There were no significant differences in the demographic features of children with and without MAS nor were there any in variables used to assess lupus outcomes, which included immunosuppressive drug use, average daily corticosteroid dose (18.3 mg/day with MAS vs. 18.6 mg/day without MAS), and the number of pediatric ICU visits (incidence rate ratio for MAS vs. non-MAS, 1.60 [95% CI, 0.74-3.18]).
Mortality was significantly higher in children with MAS, compared with those without MAS (5.3% vs. 0.3%; P = .02), although the overall number of deaths in the cohort was small (n = 3). Apart from the “acute illness which was associated with 2 deaths secondary to MAS,” the investigators said that they “did not find any significant differences in the number of deaths or damage accrual between the cohorts, including overall SLICC [Systemic Lupus International Collaborating Clinics] damage score or any specific damage feature within the score.”
The study findings were limited by several factors including the lack of validated MAS criteria for children with SLE and a lack of follow-up data on the patients beyond 18 years of age, the researchers said.
The results suggest that MAS remains a life-threatening complication in children with SLE and should be considered an important cause of mortality for them, but “if the initial presentation does not result in death, the long-term outcome seem[s] to be comparable to those without MAS,” the investigators wrote.
The researchers had no financial conflicts to disclose.
SOURCE: Borgia R et al. Arthritis Rheumatol. 2018 Jan 17. doi: 10.1002/art.40417