Four bleeding risk scores identified patients with deep vein thrombosis (DVT) or pulmonary embolism (PE) who had a low rate of major bleeding at 30 days when treated with rivaroxaban, according to Jeffrey A. Kline, MD, Indiana University School of Medicine, Indianapolis, Indiana, USA.

The investigators hypothesized that the rate of major bleeding associated with rivaroxaban treatment would be < 1% when using a bleeding risk scoring system derived to predict a low risk of bleeding in patients with venous thromboembolism (VTE) treated with a vitamin K antagonist. They used pooled data from the EINSTEIN-DVT and EINSTEIN-PE studies and found a low rate of major bleeding in the patients treated with rivaroxaban (1%; 40 of 4150 patients) [Prins MH et al. Thromb J. 2013]. Rivaroxaban was given at 15 mg twice daily for 21 days and then 20 mg once daily for 3 to 12 months.

The 4150 rivaroxaban-treated patients were stratified as low, moderate, or high risk using each of the 4 bleeding risk scores [Ruiz-Gimenez N et al. Thromb Haemost. 2008; Kuijer PM et al. Arch Intern Med. 1999; Beyth RJ et al. Am J Med. 1998; Landefeld CS et al. J Clin Epidemiol. 1989]. SMQ codes were used to extract data from the case report forms and any missing data were considered normal. The ISTH definition of major bleeding was used.

The primary outcome was the rate of major bleeding at 30 days and for the total treatment duration. During the critical 30-day period after discharge, there was a low rate of major bleeding in the low-risk patients and the confidence intervals were < 1 at 30 days and for the entire study period. The proportion of patients defined as low risk ranged from 28.7% to 63.6% depending on the score.

The characteristics associated with low risk were age < 65 years, no history of bleeding, and no comorbid conditions (current cancer, renal insufficiency, diabetes mellitus, anemia, prior stroke or myocardial infarction). These criteria identified a subgroup of patients in the EINSTEIN studies who were at low risk of bleeding and had a rate of major bleeding of < 0.5% at 30 days. Thus, patients with VTE aged < 65 years with no bleeding history or significant comorbidities can be counseled that they have a < 1 in 100 chance of experiencing a major bleeding event during the first 30 days of treatment with rivaroxaban, concluded Dr Kline. Dr Kline postulated that these bleeding risk scores could be applied in the emergency room to identify low-risk patients who may be safely discharged from the emergency department with a novel oral anticoagulant.