Hospitalization trends and clinical burden of paediatric haemophagocytic lymphohistiocytosis in a multicentre study in China.

Haemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome characterized by immune dysregulation, cytokine storm and multi-organ dysfunction. Due to the scarcity of large multicentre epidemiological studies on paediatric HLH in China, we performed a national analysis to characterize disease burden and features, providing evidence for high-risk identification and resource allocation. We analysed national epidemiological data on paediatric HLH hospitalizations in China using the FUTURE database (2016-2022; 33 children's hospitals). HLH accounted for 0.7803‰ of paediatric hospitalizations, predominantly affecting children aged 1-3 years (34.33%). From 2016 to 2022, the proportion of paediatric HLH hospitalizations showed a declining trend, with the most notable decrease observed during 2020-2022. Respiratory diseases (41.07%) were the most common concomitant condition. Infants aged 29 days to <1 year (odds ratio [OR] = 3.11, p < 0.001) and patients from Northwest (OR = 2.68, p = 0.002) and Southwest regions (OR = 1.87, p = 0.043) had higher mortality risks. Infection-associated HLH (86.09%) was the most common subtype, with Epstein-Barr virus (EBV) as the leading trigger. Central nervous system (CNS)-HLH showed higher risks of multi-organ damage. In Chinese paediatric HLH inpatients, the number of concomitant conditions positively correlated with hospital stay and costs. Different HLH subtypes exhibited distinct clinical features, highlighting the importance of tailored management approaches based on disease classification and risk stratification.