Trends in Mortality Rates From Hemophagocytic Lymphohistiocytosis in the United States From 2010 to 2023

Hemophagocytic lymphohistiocytosis (HLH) is a severe, life-threatening condition marked by uncontrolled T-lymphocyte and macrophage-mediated inflammation, usually secondary to an underlying malignancy or infection in adults. It leads to multiorgan failure and death if not promptly recognized and treated; adult secondary HLH carries an overall mortality rate of 57% in an ICU population regardless of treatment. We examined trends in age-adjusted mortality rates from the Centers for Disease Control and Prevention's Wide-ranging Online Data for Epidemiologic Research (CDC WONDER) database to further characterize this interesting multinational finding in an otherwise rare disease. Age-adjusted mortality rates (AAMRs) from HLH showed consistent yearly increases, most of which were statistically significant, with an overall 12-fold rise from 2010 to 2023. This trend was mirrored in all census regions and in most demographic categories.