RESULTS: We identified 9,638 VTE patients on rivaroxaban, 43.7% with PE with or without DVT, and 56.3% with DVT without PE. MB was identified within 130 VTE patients; 74 (56.9%) with DVT and 56 (43.1%) with PE. The overall VTE cohort had a MB incidence rate of 2.47 (95% CI 2.08-2.93) per 100 person-years, primarily in gastrointestinal sites. MB incidence was higher in the DVT cohort versus PE, 2.74 and 2.18 per 100 person-years respectively. Females accounted for 63% of MB patients and 47% of non-MB patients. Mean (SD) age of MB cases was 66.6 (16.8), versus 60.8 (17.5) years among the non-MB group. In general, patients with MB had higher prevalence of comorbidities than those without. Multivariate analyses found the following covariates significantly associated with MB: sex, dementia, anemia, and history of MB. Age was retained in the model due to its confounding relationship with dementia. Adjusted hazard ratios for the significant covariates were: females 1.60 (95% CI 1.11-2.29), dementia 2.01 (95% CI 1.30-3.12), anemia 2.57 (95% CI 1.77-3.73), and history of bleeding 2.73 (95% CI 1.41-5.26). Fatal bleed rate in the overall cohort was 0.06 (95% CI 0.02-0.18) per 100 person-years.