Paediatric macrophage activation syndrome: clinical features and outcomes across diverse aetiologies.

Compared with sJIA, non-sJIA had higher intensive care unit admission (72.7% vs 25.0%, P = 0.02) and mortality (21.6% vs 6.3%, P = 0.04), whereas recurrence was more common in sJIA (28.1% vs 9.1%, P = 0.04).

Stratified analyses (multisystem inflammatory syndrome in children, other macrophage activation syndrome and sJIA) showed higher intensive care unit admission in multisystem inflammatory syndrome in children and other macrophage activation syndrome, highest mortality in other macrophage activation syndrome and highest recurrence in sJIA, with rates of 77.3%, 68.2% and 25.0% (P < 0.001), 6.8%, 36.4% and 6.3% (P < 0.001), and 2.3%, 15.9% and 28.1% (P = 0.01), respectively.