Abstract Number: OC 53.2
Meeting: ISTH 2021 Congress
Background: Hereditary TTP is a rare thrombotic microangiopathy caused by bi-allelic ADAMTS13 mutations leading to severe ADAMTS13 deficiency. Recently published follow-up data from the IHTTP Registry showed a heterogeneous clinical course: 43/87 patients experienced 131 acute episodes during 371 patient-years of prospective follow-up*.
Aims: We updated the incidence of prospectively observed acute episodes in hTTP pediatric patients (children, adolescents, young adults) up to the age of 18 years.
Methods: At the end of 2020, we followed 30 hTTP pediatric patients from 22 centers in 16 countries. The annual incidence of acute episodes was calculated as number of episodes/years of total follow-up.
Results: 14/30 hTTP pediatric patients experienced 100 episodes: 36 episodes occurred in 4 hTTP pediatric patients under plasma prophylaxis, 19 in 5 patients treated on demand, and 45 in 5 patients with intermittent prophylaxis. No episode was fatal. The annual incidence of acute episodes decreased with increasing age: from 1.99 (95%CI 0.96-3.66) in 5 patient-years in early childhood (>3 month to ≤6 years) to 0.84 (95%CI 0.63-1.09) in 65 patient-years in late childhood/adolescence (>6 to <18 years). For comparison, the annual incidence was 0.22 (95%Cl 0.13-0.36) in adults*. Ninety-four episodes were considered mild (score 1) with thrombocytopenia, fever and mild general symptoms*. Six episodes were classified as moderate (score 2) to severe with acute renal failure and neurological involvement (score 3) with the potential of lasting sequelae*.
Conclusions: Prophylactic plasma treatment as currently performed in many centers is often not sufficient to prevent the occurrence of acute episodes in pediatric patients. This may be due to the difficulty of performing regular plasma infusions every two-to-three weeks and due to the highly sensitive life period. The advent of recombinant ADAMTS13 with the possibility of home-treatment may ease prophylaxis, especially in children.
* Tarasco et al, Blood 2021, doi: 10.1182/blood.2020009801.
To cite this abstract in AMA style:Tarasco E, Sakai K, Al Shanbary S, Bütikofer L, El Chazli Y, N George J, Hengartner H, Jalal S, N Knöbl P, Maaß E, Milanovich S, Perungo S, Sinkovits G, Steele M, von Krogh AS, Wyatt K, Lämmle B, Kremer Hovinga JA, other members Steering Committee international hTTP Registry . Children with Hereditary Thrombotic Thrombocytopenic Purpura (hTTP) Have a High Incidence of Acute Episodes: Data from the International Hereditary TTP Registry (IHTTP Registry) [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/children-with-hereditary-thrombotic-thrombocytopenic-purpura-http-have-a-high-incidence-of-acute-episodes-data-from-the-international-hereditary-ttp-registry-ihttp-registry/. Accessed November 29, 2021.
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