Paediatric macrophage activation syndrome: clinical features and outcomes across diverse aetiologies
Authors' conclusion
Paediatric MAS is aetiologically heterogeneous, with inflammatory burden and organ dysfunction driving poor outcomes. Immune-regulatory variants are linked to severe or relapsing disease
Study context
- Population
- Children with macrophage activation syndrome (MAS) across diverse aetiologies
- Participants
- 120 children
- Exposure
- Non-sJIA vs systemic juvenile idiopathic arthritis (sJIA) aetiology of paediatric MAS
- Outcome
- Outcomes of paediatric MAS (whole cohort)
Methodological detailsmultivariable logistic regression
- Multivariable logistic regression
Main finding
As reported in the abstract
- Intensive care unit (ICU) admission
- 60%
- Acute organ failure
- 45%
- Mortality
- 17.5%
- Aetiology: Multisystem inflammatory syndrome in children (MIS-C)
- 36.7%
- Aetiology: sJIA
- 26.7%
- Aetiology: infection-triggered MAS
- 23.3%
- Aetiology: other rheumatologic diseases
- 10.8%
- Aetiology: lymphoma
- 2.5%
Observational data: associations, not effects.
Further findings
| Outcome | sJIA | non-sJIA | MIS-C | Other MAS | P value |
|---|---|---|---|---|---|
| ICU admission, non-sJIA vs sJIA | 25.0% | 72.7% | — not stated in the abstract | — not stated in the abstract | P = 0.02 |
| Mortality, non-sJIA vs sJIA | 6.3% | 21.6% | — not stated in the abstract | — not stated in the abstract | P = 0.04 |
| Recurrence, sJIA vs non-sJIA | 28.1% | 9.1% | — not stated in the abstract | — not stated in the abstract | P = 0.04 |
| ICU admission, stratified (MIS-C, other MAS, sJIA)MIS-C vs Other MAS · across the three strata | 25.0% | — not stated in the abstract | 77.3% | 68.2% | P < 0.001 |
| Mortality, stratified (MIS-C, other MAS, sJIA)Other MAS vs MIS-C · across the three strata | 6.3% | — not stated in the abstract | 6.8% | 36.4% | P < 0.001 |
| Recurrence, stratified (MIS-C, other MAS, sJIA)sJIA vs MIS-C · across the three strata | 28.1% | — not stated in the abstract | 2.3% | 15.9% | P = 0.01 |
— not stated in the abstract
Hemophagocytic Lymphohistiocytosis (HLH)-related genetic variants (tested subgroup)
- Carriers of HLH-related variants among tested patients
- 22.4%
- Variant positivity independently associated with higher ferritin, younger MAS onset, recurrence, acute organ dysfunction and sJIA aetiology
Predictors of outcomes (multivariable)
- Higher peak ferritin and mortality, OR
- 2.01
- Higher peak ferritin and remission off therapy, OR
- 0.70
- sJIA aetiology and mortality, OR
- 0.21
Original publication
Paediatric macrophage activation syndrome: clinical features and outcomes across diverse aetiologies. Rheumatology (Oxford). Published 8 July 2026. doi:10.
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