Evaluation of ISTH Severe Bleeding Criteria and Development of a Mortality Prognosis Model for Hospitalized Immune Thrombocytopenia Patients: A Multicenter, Retrospective and Prospective Cohort Study

Introduction: Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by the immune system's erroneous destruction of platelets, which play a crucial role in blood clot formation. This condition precipitates a decreased platelet count and consequently heightens the risk of bleeding events, ranging from mild petechiae to severe, potentially fatal occurrences such as intracranial hemorrhage. Therefore, accurate anticipation and management of these severe bleeding risks form an integral facet of clinical care for ITP patients. The International Society on Thrombosis and Hemostasis (ISTH) has instituted criteria designed to classify and forecast severe bleeding in patients with thrombotic disorders. Despite their widespread use in diverse clinical scenarios, the validity and efficacy of these criteria for ITP patients remain underexplored. Furthermore, disparities in the application and interpretation of these criteria among practitioners underscore the necessity for a comprehensive evaluation within the ITP context. Consequently, our study is poised to fill these crucial gaps. We intend to evaluate the performance and applicability of the ISTH severe bleeding criteria specifically within the ITP patient population. Concurrently, we aspire to develop and validate a robust, reliable mortality prediction model for this unique group of hospitalized patients. Methods: This study was a multicenter, retrospective cohort investigation conducted across 20 medical centers nationwide. A total of 1487 adult patients diagnosed with immune thrombocytopenia were enrolled. The study period spanned from Jan 2020 to Jan 2023, ensuring a comprehensive assessment of patient outcomes. To further evaluate the joint impact of multiple prognostic factors, a multivariate Cox regression model was constructed. Prospective observational cohorts were subsequently established with the objective of assessing the real-world performance of the mortality prognosis model. Results: In our study, out of the 1487 enrolled adult patients with immune thrombocytopenia (ITP), 420 patients (28.24%) experienced bleeding events. The incidence of major bleeding types among these patients was assessed based on the critical bleeding diagnostic criteria. Intracranial bleeding was found to be the most common type, occurring in 229 patients (54.46%). This was followed by respiratory compromise in 87 patients (20.66%) and hemodynamic instability bleeding in 76 patients (18.08%). Intramuscular ble