Development and Initial Validation of a Novel Prognostic Model in Adult Secondary Hemophagocytic Lymphohistiocytosis Patients: Experience From a Single-center Retrospective Study

Abstract Objectives: To describe the prognostic factors of adult patients diagnosed with secondary hemophagocytic lymphohistiocytosis (HLH), a rare disease caused by excessive immune activation and uncontrolled cytokine storm, and to establish and initially validate the predictive value of a prognostic model.Methods: We conducted a retrospective cohort study of 204 adult secondary HLH patients from January 2010 to December 2018 (the development cohort, n=161) and January 2019 to December 2020 (the validation cohort, n=43). All patients met ≥5 HLH-2004 criteria. Prognostic variables to death within three months at diagnosis were selected by logistic regression models, and performance of the predictive model was assessed in development and validation cohort, respectively.Results: Of all patients, malignancies were the most common trigger, accounting for 61.3%. Patients with poor prognosis showed lower hemoglobin (P<0.001), platelets (P<0.001), albumin (P=0.007) and fibrinogen (P=0.002), and higher levels of total bilirubin (P=0.007), LDH (P=0.033), BUN (P=0.006), and TG (P=0.015). Furthermore, patients with poor prognosis had a higher ISTH score (P<0.001). In the development cohort, a predictive model was established based on four variables (splenomegaly, hemoglobin, LDH and ISTH score) recognized by the multivariate logistic regression, with the cut-off value of 0.277 reaching a sensitivity of 87.7%, specificity of 49.0% and AUC of 0.731 (95%CI 0.651-0.810, P<0.001). Besides, the model could perform well in the validation cohort, with a sensitivity of 53.8%, specificity of 40.0% and accuracy of 44.2%.Conclusions: Our predictive model provides a possibility of forecasting the prognosis of adult patients within three months at diagnosis of secondary HLH, while more large sample, multicenter, randomized controlled clinical research are needed to confirm it.