Investigation of the relationship between red blood cell distribution width and mortality in patients with hemophagocytic lymphohistiocytosis: a retrospective study

Abstract

INTRODUCTIONHemophagocytic lymphohistiocytosis (HLH) is a high inflammatory response syndrome, wherein uncontrolled immune activation leads to multiple organ failure, with high mortality. 1,2 Impaired immune function, such as that of natural killer (NK) or T cells, is a key factor in the occurrence of HLH. 1,3 Overactivation of macrophages can induce hemophagocytosis and a cytokine storm, resulting in clinical manifestations, such as fever, enlargement of the liver and spleen, and reduction of extracellular cells. 4,5 The concept of HLH was proposed by two pediatricians, Scott and Robb Smith, in 1939. 6 Therefore, our understanding of HLH was initially concentrated in children, and adult HLH was gradually recognized. 7 Adult HLH in Italy, Sweden, and the United States have an annual incidence rate of 1 per 800,000 people. 8,9 Increasing annual infections, tumors, and autoimmune diseases are the leading causes of secondary adult HLH in China. 10,11 Red blood cell distribution width (RDW), derived from whole blood count, is a parameter reflecting the volume heterogeneity of red blood cells that can classify anemia. 12,13 Elevated RDW is considered an inflammatory marker that can predict the adverse prognosis of various diseases, including heart failure, acute renal injury, sepsis, and cancer. Platelets play an important role in regulating inflammation and innate immunity. 13,14 They adhere to endothelial cells during acute inflammation, mediating neutrophil chemotaxis, infiltration, and secretion of pro-inflammatory chemokines. Severe infection can lead to a decreased platelet count. Studies 15,16 have shown that platelet count is a predictor of mortality. Adult secondary HLH is associated with rapid progress and high mortality. More biological indicators are needed to predict patients' mortality as they have attracted clinicians' attention and improved patient vitality thus far.