Blood thinner study targets dosing mystery in obesity and bariatric patients

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Creatinine clearance measured by the Cockroft formula ≥ 60 mL / min * Patient meeting the specific criteria of one of the 4 groups: * morbidly obese patients with BMI ≥ 40 * Patients operated by gastric bypass for over a year and with stable weight * Patients operated by sleeve gastrectomy for over a year and with stable weight * Control group: non-operated subjects but with an age and a BMI corresponding to those of the patients of the 2 operated groups. Exclusion Criteria: * Indication for anticoagulant therapy, antiplatelet therapy or long-term nonsteroidal anti-inflammatory drugs * Clinically significant bleeding in progress * Taking oral or parenteral anticoagulants, or taking platelet antiaggregants within 4 weeks before inclusion * Congenital or acquired hemorrhagic disorders (eg von Willebrand disease, hemophilia) * Injury or disease, at significant risk of major bleeding (gastrointestinal ulceration, presence of malignant tumors with a high risk of bleeding, recent brain or spinal cord injury, recent cerebral, spinal or ophthalmic surgery, recent intracranial hemorrhage, known or suspected oesophageal varices , arteriovenous malformations, vascular aneurysms or major intraspinal or intracerebral vascular abnormalities) * Severe uncontrolled arterial hypertension * Active gastrointestinal disease potentially leading to bleeding disorders (esophagitis, gastritis, gastroesophageal reflux disease, chronic inflammatory bowel disease) * Vascular retinopathy * Bronchiectasis or history of pulmonary bleeding * Hypersensitivity to the active substance or to any of the excipients of rivaroxaban * Hepatic involvement associated with coagulopathy and clinically significant bleeding risk, including cirrhotic patients with Child Pugh Grade B or C score * Concomitant use of potent inhibitors or inducers of CYP3A4 and / or P-gp (azole antifungal or HIV protease inhibitor) * Participation in a paid and / or therapeutic study in the previous 3 months * Pregnant or lactating women, * Women of childbearing potential not using effective contraception