Dissecting the heterogeneity of macrophage activation syndrome

Methods Patient data were collected retrospectively by pediatric rheumatologists (PR) or pediatric hemato-oncologists (PHO). Clinical features, treatments and outcome were compared between groups by Mann-Whitney or chisquare tests. “Severe course” was defined as ICU admission or death. Results 362 patients with MAS in sJIA were collected by 95 investigators from 33 countries. 179 patients (49.4%) were enrolled in Europe (EU), 72 (19.9%) in North America (NA) and 111 (30.7%) in other continents (OC). 79 (21.8%) patients were included by PHO. HP was detected in 44% of patients and was not detected or looked for in 56%. Severe course was reported in 92 (25%) patients. Comparison by geographic origin showed a lower frequency of CNS disease in EU patients. NA physicians used more frequently ivIg and biologics. Patients entered by PHO had greater frequency of multiorgan failure and were given more commonly biologics and etoposide, whereas PR used more frequently cyclosporine (CsA). Patients with HP had shorter duration of sJIA at MAS onset, higher prevalence of hepatosplenomegaly, lower levels of platelets and fibrinogen and received more frequently CsA, ivIg and etoposide. Patients with severe course were older, had longer duration of sJIA at MAS onset, greater frequency of haemorrhages and CNS dysfunction, lower levels of ESR, albumin and fibrinogen, higher levels of LDH and D-dimer and were treated more commonly with CsA, ivIg and etoposide. Conclusion