Risks and outcomes of gastrointestinal malignancies in anticoagulated atrial fibrillation patients experiencing gastrointestinal bleeding: A nationwide cohort study

Background: Oral anticoagulants (OACs) may serve as a “screening test” for gastrointestinal (GI) tract malignancies through the clinical presentation of bleeding. Objective: The purpose of this study was to investigate the 1-year incidence and predictors of GI cancer after GI bleeding among atrial fibrillation (AF) patients treated with warfarin or non-vitamin K antagonist oral anticoagulants (NOACs). The risks of mortality after GI cancers between patients receiving warfarin and those receiving NOACs were compared. Methods: A total of 10,845 anticoagulated AF patients hospitalized due to GI bleeding without a previous history of GI cancer were identified from the Taiwan National Health Insurance Research Database. Patients were followed-up for incident GI cancers for up to 1 year. Results: Within 1 year after GI bleeding, 290 patients (2.67%) were diagnosed with GI tract cancer. More patients treated with NOACs were diagnosed with GI cancer than those treated with warfarin (3.87% vs 2.44%; P <.001; odds ratio [OR] 1.606; P <.001). Age (OR 1.025 per 1-year increment) and male sex (OR 1.356) were associated with the diagnosis of GI cancer. Among patients diagnosed with GI cancer, 45.2% died within 1 year. The risk of mortality was lower in patients treated with NOACs than in those treated with warfarin (23.5% vs 51.8%; adjusted hazard ratio 0.441; P <.001). Conclusion: Incident GI cancers were diagnosed in 1 of 37 AF patients at 1 year after OAC-related GI bleeding and were more common among patients treated with NOACs (1/26) compared to warfarin (1/41). Detailed examinations for occult GI cancers are necessary, especially among elderly males.