[Effect of Plasma Epstein-Barr Virus Nucleic Acid Loads on the Clinical Features and Prognosis in Adult Secondary Hemophagocytic Lymphohistiocytosis].

Objective: To investigate the effect of pre-treatment plasma Epstein-Barr virus (EBV) DNA copy number on the clinical features and prognosis of patients with adult secondary hemophagocytic lymphohistiocytosis(sHLH).

Methods: The clinical characteristics, survival rate, and prognostic factors of 171 patients with adult sHLH treated at Jiangsu Province Hospital from June 2017 to January 2022 were retrospectively analyzed in this study. Patients were divided into three groups, including the EBV DNA-negative group(<5.0×10² copies/ml), lower EBV-DNA loads group(5.0×10²-8.51×10⁴ copies/ml), and higher EBV-DNA loads group(＞8.51×10⁴ copies/ml), according to pre-treatment plasma EBV-DNA copy number. Cox regression model was established for screening prognostic factors. Adult sHLH survival prediction model was constructed and realized through the nomogram based on EBV-DNA load after adjusted the factors affecting survival of etiology and treatment strategy.Concordance index (C-index) and calibration curves were calculated to verify model predictive and discriminatory capacity.

Results: Among 171 adult sHLH patients, 84 patients were not infected with EBV (EBV DNA-negative group), and 87 with EBV (EBV DNA-positive group, 48 lower EBV-DNA loads group and 39 higher EBV-DNA loads group). Consistent elevations in the levels of liver enzymes (ALT and AST), LDH, TG, β ₂-microglobulin and ferritin across the increasing of EBV-DNA load (all P <0.05), while the levels of fibrinogen decrease (P <0.001). The median follow-up time was 52 days (range 20-230 days), and 123 patients died. The overall survival (OS) rate of patients in EBV DNA-positive group was lower than that in EBV DNA-negative group (median OS: 40 days vs 118 days, P <0.001). Higher EBV-DNA loads had worse OS (median OS: 24 days vs 45 days vs 118 days, P <0.0001 for trend) compared to lower EBV-DNA loads and EBV DNA-negative group. Multivariate Cox analysis revealed that higher EBV-DNA loads (P =0.005), fibrinogen≤1.5 g/L (P ＝0.012), ferritin (P ＝0.041), associated lymphoma (P ＝0.002), and anti-tumor based strategy (P ＝0.001) were independent prognostic factors for OS. The C-indexes of 30 day, 90 days, 365 days survival rate were all greater than 0.8 of the nomogram model and calibration curves provided credibility to their predictive capability. Subgroup analysis showed that patients with higher EBV-DNA loads had a significantly worse prognosis in adult sHLH who were women, ferritin＞5 000 μg/L, β₂-microglobulin＞7.4 mmol/L and regardless of age, etiologies, HScore points.

Conclusion: The EBV-DNA load is a strong and independent predictor for survival in patients with sHLH. The prognostic nomogram based on EBV-DNA loads was dependable and provides a visual tool for evaluating the survival of adult sHLH.