Racial Variation in ITP Prevalence and Rate of Chronic Disease Suggests Biological Differences

Background: Immune thrombocytopenia (ITP) is the most common cause of acquired immune platelet destruction in children. Clinical symptoms range from asymptomatic to significant and even life-threatening bleeding, fatigue, and reduced health-related quality of life. About 75% of affected children experience spontaneous remission, with the remainder developing chronic ITP. Our clinical observations suggest a decreased prevalence of ITP among Black children, although no available studies have evaluated racial or ethnic predisposition to ITP or to chronic disease. We hypothesized that biological differences in Black children alter the prevalence of ITP, relative to the general population, and may affect disease course. Methods: A retrospective analysis evaluating race and ethnicity of all children with ITP treated at Texas Children's Hospital (TCH, Houston, TX) from January 2015-July 2019 was performed, and compared to both the Houston metropolitan area and the TCH Cancer Center 2018 race and ethnicity data. Of the 699 unique patients, race and ethnicity data were unavailable for 24, and 2 patients were excluded (1 with leukemia, 1 with bone marrow failure). The remaining patients were categorized as (1) White, non-Hispanic; (2) Black, non-Hispanic; (3) Hispanic; and (4) Other. Hispanic patients included those who self-identified as (1) White, Hispanic; (2) Black, Hispanic; (3) Asian, Hispanic; (4) Multi-race, Hispanic; and (5) Unknown race, Hispanic. Demographic data was then collected in a second ITP population derived from the Children's Hospital of Philadelphia (CHOP, Philadelphia, PA) and the surrounding metropolitan area. To match the distribution reported in the Houston metro area data, a comparison was conducted focusing on the proportion of Black non-Hispanic patients in each cohort. A chi-squared test with Yates correction was utilized to compare nonparametric categorical data using GraphPad Prism version 8.0.1 for Windows, GraphPad Software, San Diego, California, USA. A p-value of