Direct oral anticoagulants (DOACs) are an attractive choice for patients in need of anticoagulant therapy, but available data on their specific use in real life conditions in elderly patients are limited. The purpose of this study is to describe the characteristics and evolution of the prescriptions in geriatric hospital.
The prescriptions of patients treated with DOACs in two university geriatric hospitals were analyzed retrospectively over 3 years. Co-treatment and hemorrhagic and thrombotic complications were studied.
A total of 399 patients were included, including 10 in 2015, 110 in 2016 and 279 in 2017. The average age was 85 years old, 40% of patients had a weight of less than 60kg, and more than 50% had an estimated creatinine clearance of less than 50mL/min. The most common indication was atrial fibrillation in 85%. In 32% of cases, the dosage of DOACs was not adapted to official recommendations. Underdosages accounted for approximately 60% of dosage errors. Twelve patients (3% of the cohort) had a thrombotic event under DOACs, associated with an underdosing in 50% of them. 41 patients, or 10% of the cohort, had a hemorrhagic event under DOACs, with 12 patients (29%) having a pharmacologic risk factor (10 overdoses and 2 drug interactions).
The prescription of DOACs in elderly patients has increased considerably in recent years. However, dosing errors remain frequent (overdoses as underdoses), associated with hemorrhagic or thrombotic events. Similarly, drug interactions should be known as they are a risk factor for avoidable under- or overdose. Improving prescriptions of DOACs in geriatrics needs to respect the rules of good practice, to regularly reassess renal function, and to transmit observations of adverse effects to pharmacovigilance centers.

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