Rivaroxaban for a Patient with Class III Obesity: Case Report with Literature Review

Between 1985 and 2011, the prevalence of obesity, defined as body mass index (BMI) of 30 kg/m2 or higher, increased from 6.1% to 18.3% in Canada.1 It is estimated that by 2019, more than 55% of the adult Canadian population will be overweight or obese.1 Obesity is associated with an approximately 2-fold increased risk of venous thromboembolism (VTE).2 The major mechanisms proposed as being responsible for obesity-associated thrombosis are chronic inflammation, impaired fibrinolysis, and clinical factors such as immobility, obstructive sleep apnea, heart failure, and venous stasis.2 Direct oral anticoagulants (DOACs) are indicated for the prevention of acute VTE in patients who have undergone elective hip or knee replacement, for the treatment of acute VTE, for the prevention of recurrent VTE, and for the prevention of stroke or systemic embolism in patients with atrial fibrillation. The Canadian rivaroxaban product monograph states that for patients with extremes of body weight (< 50 kg or > 120 kg), a 10-mg tablet caused less than a 25% change in the plasma concentration of rivaroxaban, and thus no dosage adjustment is required.3 The 2016 guidelines of the International Society on Thrombosis and Haemostasis (ISTH) suggest that DOACs not be used in patients with weight greater than 120 kg or BMI greater than 40 kg/m2 because of the lack of clinical data for this population.4 We present here a case of rivaroxaban use in a patient with class III obesity and review the evidence for use of this medication in obese patients