PB0294 - Adolescent Thrombotic Thrombocytopenic Purpura is a Serious Disorder Requiring Intense Therapies with Significant Morbidity and Relapse

Background: Thrombotic thrombocytopenic purpura (TTP) is a rare hematologic condition with a paucity of data in adolescents.

Aims: To study the clinical characteristics, treatments, and outcomes in adolescents diagnosed with acquired TTP between 2009-2020 using the Pediatric Health Information System (PHIS) database.

Methods: The PHIS database was queried to identify adolescents ages 10-21 years with the Internal Classification of Diseases (ICD-9 and -10) codes for thrombotic microangiopathy from 2009-2020. Inclusion criteria included the ICD lab test code for ADAMTS-13 and procedure codes for therapeutic plasmapheresis, consistent with treatment for acquired TTP. Exclusion criteria included ICD procedure codes for hemodialysis and peritoneal dialysis, diagnostic code for hemolytic-uremic syndrome, and drug code for eculizumab. Primary outcomes evaluated were mortality and relapse, defined as hospital readmissions requiring plasmapheresis. Patient demographics, clinical characteristics, treatment, and outcome data were collected. Statistical analysis included the use of Fisher’s exact, Chi-squared, and Wilcoxon rank sum tests.

Results: A total of 99 patients with 123 hospitalizations for TTP were identified. Patient demographics are noted in Table 1. Hospitalization and patient outcome characteristics are noted in Table 2. Second-line therapies were required in 76 (62%), ICU admissions in 85 (69%), mechanical ventilation in 33 (27%), and ECMO in 2 (1.6%) of hospitalizations. Twenty patients (20%) had at least one TTP relapse requiring subsequent hospitalization and plasmapheresis. The median time to relapse from initial hospitalization was 33 days (IQR 15, 92). There were 12 hemorrhagic, 4 thrombotic complications and 6 deaths (6%). No statistically significant differences were noted when comparing demographics, time-period of diagnosis, and the presence of comorbidities of patients with and without mortality or relapse.

Conclusion(s): Adolescent TTP is a serious disorder requiring intense therapies, with significant morbidity and apparent higher relapse when compared to adults. Multicenter studies are needed to develop optimal treatment strategies to improve the outcome of adolescent TTP.