PB0332 - Hereditary thrombotic thrombocytopenic purpura: A survey of Canadian Treaters

Background: hTTP is an ultra-rare disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ damage by microthrombi and caused by a defect in the ADAMTS13 gene. hTTP affects approximately 1 in 1,000,000 people and is expected to affect 38 Canadians. However, no Canadian data exist on the prevalence or treatment of this condition.

Aims: The objective was to survey Canadian physicians on the prevalence, significance, and treatment of hTTP in Canada.

Methods: We conducted an electronic survey (SurveyMonkey®) of physicians, mainly hematologists, to collect data on their hTTP patients. Participants were given 4 months to complete the survey between August 2021 and December 2021. The survey collected data on prevalence, disease burden and treatment of hTTP patients. Descriptive analysis was used to analyze the results.

Results: We received 48 responses. Of these responses, 23 respondents(47.9%) have managed at least one hTTP patient in their careers. All respondents practiced in academic centres, with 83% treating adult patients. Over the course of their practice, the respondents have collectively managed 29 hTTP patients. Most physicians managed 1(57.9%) or 2(31.6%) hTTP patients. At the time of the survey, 14 patients were actively managed and 12/14(85.7%) had ADAMTS13 genetic testing done. 11/14(78.6%) have experienced at least one acute episode of TTP and/or organ damage. 6/14(42.8%) of patients have had at least one stroke and 3/14(21.4%) have a permanent disability. Out of all the patients that were ever managed by the respondents, 2 have died because of disease complications (Figure 1). 11/14(78.6%) patients are on prophylactic plasma infusions.

Conclusion(s): Our survey has important limitations (may not have captured all physicians looking after hTTP Canadian patients, potential for recall bias), but provides the first Canadian data on this condition. hTTP is a rare disease associated with significant morbidity. Future direction includes development of a Canadian registry for hTTP patients.