PB1332 - Heightened Thrombosis in Immune Thrombocytopenia: Insights into the Risk Factors and clinical outcomes from an Australian hospital cohort

Tuesday, June 27, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

IG

Isaac Goncalves, MD PhD

Haematologist
Peter MacCallum Cancer Centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia

Co-Author(s)

KM

Kylie Mason

Haematologist
Peter MacCallum Cancer centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia
JS

Jeffrey Szer

Haematologist
Peter MacCallum Cancer centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia
RD

Rebecca Dring

Research Nurse
Peter MacCallum Cancer centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia
BG

Brian Grainger

Haematology Fellow
Peter MacCallum Cancer centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia
CL

Cameron Lewis

Haematology Registrar
Peter MacCallum Cancer centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia
NL

Nora Lee

Haematology Registrar
Peter MacCallum Cancer centre and Royal Melbourne Hospital
Melbourne, Victoria, Australia
RH

Rachael Howe

Research Nurse
Bendigo Health
Bendigo, Victoria, Australia

Background: There is evidence that patients with Immune Thrombocytopenia (ITP) are at increased risk of thromboembolism (TE). The association between clinical and treatment -related factors with thrombosis remain controversial.

Aims: To evaluate the incidence and risk factors for TE in patients with ITP and describe clinical outcomes.

Methods: Retrospective cohort study (January 1, 2011 – October 30, 2022) of adult patients diagnosed with ITP from an Australian tertiary hospital. The incidence rates of thrombosis were calculated in terms of person-years of follow-up. Multi-adjusted cox-regression was used to estimate associations.

Results: A total of 220 patients with 1365 person-years of follow-up since ITP diagnosis revealed 26 (11.8%) patients with a total of 37 TE events, 28 (75%) Venous TE (VTE) and 9 (25%) Arterial TE (ATE) (Table 1). The incidence rate of TE was 27.1 [6.6 (ATE) and 20.5 (VTE)] per 1000 person-years. Age (HR, 1.041, 95%CI, 1.020-1.063), secondary ITP (HR, 2.625, 95%CI, 1.196-5.761) and Thrombopoietin receptor agonist therapy (HR, 3.154, 95%CI, 1.451-6.857) were independently associated with TE (Table 2). Median age and time to first TE diagnosis was 57 years (IQR 41 – 74), and 20 months (IQR 3.3 – 50.8), respectively. Median platelet count at TE diagnosis was 144 (IQR 97 – 191). Eight of 9 ATE events were treated with anti-platelet agents, 26 of 28 (92.9%) VTE events were treated with anticoagulation. Seven (27%) patients experienced (Grade 1 – 2) bleeding with TE treatment. Recurrent TE occurred in 7 (27%) patients, 2 occurred while receiving TE therapy. Five (19%) died at last follow-up, 1 was due to VTE.

Conclusion(s): Thromboembolism is prevalent and a clinically challenging problem in patients with chronic ITP. Our findings demonstrated that age, secondary ITP and TPO-RA were independent predictors of TE. Studies providing more comprehensive details of patient selection for specific ITP therapy and TE prevention are needed.