OC 32.5 - Interim analysis of the Prospective Cohort Study on Patients with a Haematological Malignancy on Anticoagulants who develop Thrombocytopaenia (HAT Study)

Monday, June 24, 2024

10:30 – 10:45 ICT

Room: Ballroom B2

Presenting Author(s)

Marcus P. Lombard, MBBS BMedSc (Hons)

Haematology Registrar
Fiona Stanley Hospital
Bicton, Western Australia, Australia

Co-Author(s)

JL

Jessica Ling

Haematology Registrar
Fiona Stanley Hospital
MURDOCH, Western Australia, Australia
Caitlin Rice, MB Bch BAO DTMH MRCP

Haematology Research Fellow
Fiona Stanley Hospital, Perth, Western Australia
Perth, Australia, Western Australia, Australia
DO

Dylan O'Donovan

Doctor
Sir Charles Gairdner Hospital
Perth, Western Australia, Australia
KC

Katherine Creeper

Haematology Consultant
Sir Charles Gairdner Hospital
Perth, Western Australia, Australia
RD

Rosslyn De Wet

Haematology Consultant
Sir Charles Gairdner Hospital
Perth, Western Australia, Australia
Dominic Pepperell

Haematology Consultant
Department of Thrombosis and Haemostasis, Fiona Stanley Hospital, Perth, Western Australia, Australia
Perth, Western Australia, Australia
SP

Stephanie P'ng

Haematologist
The Haemophilia and Haemostasis Centre, Fiona Stanley Hospital, Murdoch, Australia
Murdoch, Western Australia, Australia

Background: Anticoagulation medications pose an increased bleeding risk in patients with thrombocytopenia in the setting of haematological malignancies which is balanced against an increased risk of venous thromboembolism.

Aims: To determine the rate of bleeding and thrombosis that occurs with an anticoagulant dose adjustment protocol based on thrombocytopaenia.

Methods: An observational prospective cohort study of the ISTH risk stratified anticoagulation adjustment protocol for thrombocytopaenia (Figure 1.). The inclusion criteria were age >18 with a haematological malignancy on anticoagulation for Venous Thromboembolism (VTE) or Atrial Fibrillation (AF) with thrombocytopaenia < 100 x10^9/L.

Results: Interim analysis of 26 patients enrolled during the initial period (June 2022 until October 2023 ) with 29 instances of thrombocytopaenia. Chemotherapy regimes for acute leukemia, lymphoma and myeloma were included (Table 1). The mean number of thrombocytopenic days was 25.9 (2, 113). The protocol was followed in 18 instances (62.1%).

At 30 days there were zero arterial thromboembolism in all patients. There were zero venous thromboembolism (VTE), major bleeding and one clinically relevant non-major bleeding (CRNMB) (6.3%) in the group that followed the protocol compared to one VTE (9.1%), one instance of major bleeding (9.1%) and three instances of CRNMB (27.3%) in those with protocol deviation.

The median platelet transfusion amongst all patients was 1 (0, 5) with no difference in patients who followed the protocol 1 (0, 3) and those with protocol deviation 1 (0, 9). The median red cell transfusions amongst all patients was 0 (0, 3), and in those who followed the protocol 0 (0, 2) compared to 2 (0, 3) in those with protocol deviation.

Conclusion(s): Our ISTH guideline-based risk-stratified protocol for anticoagulation management in thrombocytopaenic patients showed low rates of bleeding and clotting supporting the use of this protocol in this high-risk group of patients.