Abstract Number: PB2430
Meeting: ISTH 2020 Congress
Background: It is unclear whether elderly patients established on NOACs are at a greater risk of exposure to these drugs which could subsequently increase their risk of bleeding.
Aims: To assess exposure to NOACs in relation to age, renal function and gender.
Methods: Medically stable hospital inpatients ≥65 years, established on either apixaban , rivaroxaban or dabigatran, were recruited. Demographics, clinical data and two blood samples were collected for estimation of trough and peak plasma drug concentration using diluted thrombin time or anti-factor Xa assay, as appropriate. Plasma NOAC concentrations were compared against those reported from seminal clinical trials.
Results: 151 patients (76 on apixaban, 61 on rivaroxaban, 14 on dabigatran) were recruited. Overall, there was up to 48-fold and 13-fold variation in trough and peak plasma drug concentrations, respectively. A significantly greater proportion of patients on apixaban had peak plasma drug concentrations within the reported ranges compared to those on either rivaroxaban or dabigatran (82.9% v 44.3% v 64.3% respectively; p< 0.001). A significantly greater proportion of patients aged 65-74 had peak NOAC concentrations within the reported ranges compared to those aged ≥75 years (82.1% v 61.8% within range; p=0.04, and 14.3% v 31.7% above range). A significantly greater proportion of female patients compared to males (37.2% v 19.2%; p=0.014) and patients with severe renal impairment compared to those with normal renal function [40% (10/25) with CrCl< 30 ml/min v 10% (2/20) with CrCl≥80ml/min; p=0.024) had peak plasma NOAC concentration above published ranges.
Conclusions: There is large variability in exposure to NOACs in hospitalised patients. The proportion of patients exceeding the plasma NOAC concentration ranges reported in clinical trials increased with increasing age, reduced renal function and being female. Whether the observed increases in NOAC exposure translates to increased risk of bleeding in such patient populations requires further investigation.
To cite this abstract in AMA style:Kampouraki E, Avery P, Wynne H, Kamali F. Variability in Exposure to Non-Vitamin K Antagonist Oral Anticoagulants (NOACs) in Hospitalised Patients [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/variability-in-exposure-to-non-vitamin-k-antagonist-oral-anticoagulants-noacs-in-hospitalised-patients/. Accessed May 16, 2022.
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