Epidemiology of refractory thrombocytopenia: A retrospective overview of SEER database

Abstract Background: Immune Thrombocytopenia (ITP) is defined as immune mediated destruction of platelets. Refractory Thrombocytopenia (RT) is characterized by persistently low platelet count or relapsing thrombocytopenia despite two or more single-line therapies including splenectomy, regardless of hemorrhagic symptoms. It is diagnosed upon excluding other possible causes of thrombocytopenia. Symptom spectrum is similar to that of ITP but is difficult to control owing to lack of response. With recent advances in treatment modalities, there is an evidence-based inclination towards combination therapies targeting multiple pathogenetic processes or precipitating synergistic effect. Specifically, Thrombopoietin receptor agonist (TPO-RAs) based regimens have proven to be exceptionally efficient. Method: Refractory thrombocytopenia cases were extracted from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2023 Sub (2000-2021) using the ICD code 9992/3. The analysis was stratified based on age, sex, race, single-agent chemotherapy, and median household income inflation adjusted to 2022. Survival curves were compared using Log-Rank test (GraphPad Prism). Results: Total 203 cases of RT were identified. Median age of diagnosis was 70 years, and the overall median of survival (MoS) was 37 months. 61.58% of the cases had expired at the study end point. Of the total cases, around 56.65% were males and 43.35% were females. RT was most commonly observed in White patients (70.94%), followed by Blacks (12.32%), Hispanics (11.82%), Asian/Pacific Islanders (3.45%), and Alaskans/Native Americans and non-Hispanics of unknown race (<1%). Survival analysis based on gender, race, single-agent chemotherapy, and median household income was statistically insignificant. The age-based median of survival was notable for 42 months for age 60 and above, while it was undefined for 0-30 years and 31-60 years, respectively. Undefined MoS was likely observed due to the lack of significant numbers of death in those age categories to calculate 50% survival probability, highlighting higher survival. Conclusions: Refractory thrombocytopenia is an exceedingly rare hematologic disorder, with only 203 cases identified between 2000-2021. Our analysis revealed that males and Caucasians were primarily affected; whereas, Alaskans/American Indians and non-Hispanics of unknown race were least impacted. Improved survival outcomes were only associated with younger age. While, race, gender, income, and single-agent chemotherapy had no influence on the overall survival. More research and analysis are warranted, particularly involving TPO-RA based combination therapy, to better understand its nature.