Abstract
BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening syndrome characterized by immune dysregulation and excessive inflammation. Although diagnostic criteria and treatment protocols of HLH are well-established for pediatric populations, managing adult HLH remains challenging. METHODS: We conducted a single-center retrospective cohort study with adult HLH using data from the First Affiliated Hospital with Nanjing Medical University (January 2015-November 2023). Patient demographics, triggers, and outcomes were analyzed. Trends in case volume, diagnostics, treatments, and 30-day mortality were assessed using Sen's slope estimator. To evaluate the COVID-19 pandemic's impact, we compared pre-/post-January 2020 data. Logistic regression, Kaplan-Meier survival analysis and resource utilization analysis were applied in the analysis. RESULTS: Among 711 HLH patients (71.1% aged 43-78 years), malignancy (45.9%) and infection (31.3%) were the predominant triggers. Cases showed a non-significant upward trend (peak increase: 103.6%; slope=2.458; p = 0.348), while 30-day mortality showed a non-significant downward trend (slope=-0.819; p = 0.402). Post-pandemic, infectious indicators (e.g., WBC) differed significantly (p<0.05), though trigger distribution was unchanged (p = 0.790). Malignancy-related HLH who received HLH-specific therapy was associated with a higher survival rate (77.7% vs. 34.1%-63.4%; p<0.001). A positive correlation between systemic corticosteroid administration and favorable clinical outcome in geriatric patient cohorts. (≥69 years; 70.7% -75.5% vs. 29.6%-42.9%; p<0.001). Mean length of hospital stay (LOS) was 21.4 ± 19.2 days. CONCLUSION: Despite advancements in pediatric HLH, adult HLH mortality remains high, driven by diagnostic delays, comorbid complexity, and lack of standardized protocols. Future efforts must prioritize: (1) adult-specific biomarkers for early diagnosis, (2) trigger-tailored immunotherapies, and (3) multidisciplinary care pathways to address multisystem involvement.