Racial Disparities in iTTP Outcomes

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare but serious hematologic disorder. Intervention with plasma exchange, steroids, and rituximab has improved outcomes for patients with acute iTTP. Since Black people are overrepresented in the U.S. iTTP patient population, investigators sought to clarify if there are racial disparities in long-term outcomes.

Using a national iTTP registry, the investigators retrospectively examined the association between race, treatment, and outcomes in patients with iTTP from 1995 to 2020. The primary outcomes were mortality and relapse-free survival (RFS) in patients with new-onset iTTP; secondary outcomes included the association between rituximab therapy and RFS in patients with new-onset iTTP and in those with relapsed disease.

The analysis included 645 patients (median age, 44 years; 71% women) with 1308 iTTP episodes; 58% were Black, 37% white, and 6% other/unknown race. During a median follow-up of 3.3 years, key findings were as follows:

• Primary outcomes:
  • Acute iTTP-associated mortality was 3.3% (35 of 1049 episodes) overall and did not differ significantly between Black (3.2%) and white patients (3.7%).
  • Black race was associated with shorter RFS (hazard ratio, 1.60).
• Secondary outcomes:
  • Adding rituximab to corticosteroids improved RFS in white patients (HR, 0.37) but not Black patients (HR, 0.96).
  • In patients with new-onset iTTP, the addition of rituximab delayed relapse; however, RFS was shorter in Black than in white patients, regardless of rituximab treatment.
  • In patients with relapsed iTTP, rituximab significantly improved RFS in white but not Black patients.