(304) The Burden of Hemophagocytic Lymphohistiocytosis in Pediatric Critical Care

Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder caused by uncontrolled immune activation and excessive cytokine production. Our study aimed to characterize the epidemiology of HLH in the Pediatric Intensive Care Unit (PICU) and quantify outcomes of PICU admission for HLH.

Methods: We analyzed data from the Healthcare Cost and Utilization Project’s State Inpatient Databases (SID) from 21 states with PICU admission flags in years 2016 and 2019. Children 0-17 years were included, though neonatal admissions were excluded. International Classification of Disease 10th edition (ICD-10) diagnosis and procedure codes were used to define HLH, associated comorbidities (e.g. sepsis, malignancy), and critical care resource utilization (e.g. mechanical ventilation). We evaluated demographic and clinical characteristics for PICU admissions with and without HLH and mortality groups among those with HLH using X2 and t-tests. Significance defined as p<.05

Results: HLH was diagnosed in 173 (0.2%) admissions among 106,329 PICU admissions. Nearly half (43%) of HLH admissions had associated sepsis diagnoses, 14% had hematologic malignancies, and 14% had rheumatologic comorbidity. Patients with HLH had higher utilization of mechanical ventilation (37% versus 17%), dialysis (12% versus 0.7%), and extracorporeal support (ECMO; 3% versus 0.4%; all p<.05) compared to other PICU admissions. Multiple organ dysfunction syndrome (MODS) was significantly higher among HLH admissions (68% versus 20%, p =0.09), with 31% of HLH patients having ≥4 systems involved. Mean hospital costs ($566K versus $100K, p=0.06) and length of stay (20 versus 4 days, p=0.03) were significantly higher among HLH admissions. Mortality was significantly higher in PICU patients with a HLH diagnosis (20% versus 2%, p=0.04). Mortality among HLH admissions was associated with dialysis, ECMO, and MODS (all p<.05).

Conclusions: Though a rare disease overall, HLH is associated with a complicated hospital course, high resource utilization, and significant mortality among PICU patients. Our data highlights the need for additional research to improve early identification of HLH and to identify effective interventions to reduce morbidity and mortality.