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    Poster Networking

    Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies

    Poster Networking Session

    PB0325 - How Rare is Rare? The First Epidemiological Study of Thrombotic Thrombocytopenic Purpura (TTP) in a Large Canadian City

    Sunday, June 25, 2023
    18:30 – 19:30 ET
    Room: Exhibition
    Background: The annual incidence of thrombotic thrombocytopenic purpura (TTP) in adults ranges from approximately 1.5-6.0 cases per million. Such epidemiological data are not well described in a Canadian population.

    Aims: We aim to report the annual incidence of TTP in Toronto, the largest Canadian urban population centre.

    Methods: All adult patients with TTP in Toronto and its surrounding areas are referred to one of two apheresis centres for treatment (St. Michael’s Hospital, University Health Network). Patients treated between 2016-2020 at these centres were included in the study. Postal code segments were collected to identify patients living in the City of Toronto (study area), the population of which was determined using publicly available census data. Data including clinico-demographic characteristics were collected using our local registries. Institutional research ethics board approval was obtained.

    Results: A total of 108 acute TTP episodes in 93 patients were treated during the 5-year study period, 42 (39%) of which occurred in 38 patients residing in the study area. Using an estimated population of 2,731,571 people, the annual incidence of TTP episodes in Toronto during the study period was approximately 3.1 cases per million. Of the 42 TTP episodes, 32 (80%) were an initial presentation; annual incidence of new TTP diagnoses was 2.3 per million. In terms of clinico-demographic data, 32 (84%) patients were female and median age at episode was 49 years (IQR 36.5, 59). All cases were immune TTP. All but one patient (98%) survived the acute TTP episode.

    Conclusion(s): We report the first estimate of incidence of acute TTP episodes and new TTP diagnoses in a large, urban Canadian regional population (3.1 and 2.3 per million per year, respectively). In addition, a large proportion of patients resided outside the study area, implying a significant distance travelled to access specialized treatment.