A novel prognostic model for adult patients with Hemophagocytic Lymphohistiocytosis.

Background: Hemophagocytic Lymphohistiocytosis (HLH) is a type of rare disease with low survival rate. We aimed to develop a model to evaluate the six-month prognosis in adult HLH patients. The data at discharge (will be called as post-treatment) for newly diagnosed adult HLH patients was collected and independent prognostic variables were selected for inclusion in the model.

Results: Three laboratory markers were confirmed to be the independent risk factors (ferritin: hazard ratio (HR) 0.101, 95% confidence interval (CI) 0.036-0.282, P<0.001; platelets: HR 4.799, 95% CI 1.884-12.223, P = 0.001; alanine aminotransferase (ALT): HR 0.423, 95% CI 0.180-0.997, P = 0.049). These were included in the final clinical prediction model. Receiver operating characteristic (ROC) curves disclosed that this model had a better discrimination (area under the curve (AUC) = 0.842, 95% CI 0.773-0.910, P < 0.001) than each of them alone and the calibration curves aligned completely with the model predictions and actual observations. Kaplan-Meier curves revealed a significant difference in the overall survival (OS) in patients stratified by the model with higher values associated with a better OS.

Conclusion: These results point out that serum ferritin, platelets and ALT levels are independent elements of OS in adult patients with HLH, and that the proposed model have a better prognostic value than any of these markers alone.