Shruti Chaturvedi, Ana G. Antun, Andrew M. Farland, Ryan Woods, Ara Metjian, Yara A. Park, Gustaaf de Ridder, Briana Gibson, Raj S. Kasthuri, Darla K. Liles, Frank Akwaa, Todd Clover, Lisa Baumann Kreuziger, J. Evan Sadler, Meera Sridharan, Ronald S. Go, Keith R. McCrae, Harsh Vardhan Upreti, Angela Liu, Ming Y. Lim, Radhika Gangaraju, X. Long Zheng, Jay S. Raval, Camila Masias, Spero R. Cataland, Andrew Johnson, Elizabeth Davis, Michael D. Evans, Marshall A. Mazepa, for the United States Thrombotic Microangiopathies Consortium
Sep 22, 2022
Race affects overall relapse risk and response to rituximab in iTTP.
Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab.
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by recurring episodes of thrombotic microangiopathy, causing ischemic organ impairment. Black patients are overrepresented in iTTP cohorts in the United States, but racial disparities in iTTP outcome and response to therapy have not been studied. Using the United States Thrombotic Microangiopathies Consortium iTTP Registry, we evaluated the impact of race on mortality and relapse-free survival (RFS) in confirmed iTTP in the United States from 1995 to 2020. We separately examined the impact of rituximab therapy and presentation with newly diagnosed (de novo) or relapsed iTTP on RFS by race. A total of 645 participants with 1308 iTTP episodes were available for analysis. Acute iTTP mortality did not differ by race. When all episodes of iTTP were included, Black race was associated with shorter RFS (hazard ratio [HR], 1.60; 95% CI, 1.16-2.21); the addition of rituximab to corticosteroids improved RFS in White (HR, 0.37; 95% CI, 0.18-0.73) but not Black patients (HR, 0.96; 95% CI, 0.71-1.31). In de novo iTTP, rituximab delayed relapse, but Black patients had shorter RFS than White patients, regardless of treatment. In relapsed iTTP, rituximab significantly improved RFS in White but not Black patients. Race affects overall relapse risk and response to rituximab in iTTP. Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab treatment. How race, racism, and social determinants of health contribute to the disparity in relapse risk in iTTP deserves further study.