OC 62.5 - Direct oral anticoagulant prescribing in patients with a very low bodyweight – experience from King’s College Hospital

Background: There is little published experience of prescribing direct oral anticoagulants (DOAC) in patients with low body weight (≤50kg). This cohort is increasing due to an aging population as well as more patients receiving DOACs for the treatment of cancer- associated venous thromboembolism (VTE). Our standard practice in this group has been to perform a DOAC plasma concentration to ensure they are not over-exposed to anticoagulation.

Aims: To describe our experience of prescribing DOACs for patients with a body weight ≤50kg.

Methods: Patients prescribed a DOAC for atrial fibrillation and VTE, weighing ≤50kg who had a DOAC plasma concentration performed between 01/01/2018-31/12/2019, were identified from anticoagulation clinic records. Each case was reviewed and along with reporting the DOAC plasma concentration, 90 day outcomes (thrombosis and bleeding) from commencing the DOAC were identified from the medical records. Descriptive statistics was used to analyse the data.

Results: In total 95 patients were prescribed a DOAC during this period (Table 1 for detailed demographics). Patients were anticoagulated with apixaban 5mg bd (2.1%), apixaban 2.5mg bd (55.8%), edoxaban 30mg od (31.6%), and rivaroxaban 15mg od (10.5%). Nineteen patients had an active cancer diagnosis and 17 had documented poor dietary intake. No thrombotic complications occurred during 90 day follow-up. There were 2 episodes of major bleeding and 3 episodes of clinically relevant non-major bleeding. DOAC plasma concentrations are illustrated in Figure 1. Seventeen patients had true trough concentrations performed and all were within the expected reference range.

Conclusion(s): Low bodyweight patients are growing in number; often elderly, with significant renal impairment or a background of malignant disease. In our experience to date, exposure to the DOACs were within the respective reference ranges. Further data from a larger population is required to demonstrate safety from a bleeding perspective.