590 Gastrointestinal Bleeding in Veterans on Oral Anticoagulants

Abstract

INTRODUCTION: Oral anticoagulants play an integral role in the prevention and treatment of cerebral and systemic thromboembolism. Traditionally, this has been managed with vitamin K antagonists, primarily warfarin. Over time, however, the use of direct oral anticoagulants (DOACs) have gained popularity. Unsurprisingly, the initiation of a medication that decreases the blood's ability to clot increases the risk of bleeding. The aim of this study was to examine the incidence of gastrointestinal bleeding (GIB) in patients enrolled in an anticoagulation clinic at a Veterans Affairs (VA) medical center. METHODS: The VA's Computerized Patient Record System was used to create a list of patients seen in the VA anticoagulation (AC) clinic from 10/2010 to 9/2016. A sample of 1997 patients was randomly selected using a web-based program. Based on the formulary at the VA, only warfarin, rivaroxaban, dabigatran, and apixaban were examined. Demographics, indications for anticoagulation, and relevant comorbidities and concomitant medications were recorded. RESULTS: Despite increasing use of DOACs since their introduction in 2011, results of the analysis indicate warfarin was still the most commonly prescribed anticoagulant in our population with 1270/1997 (64%). Rivaroxaban was taken by 28%, apixaban by 13%, and dabigatran by 10%. GIB was seen in 31/1270 patients (1.55%). In those taking warfarin, 28/1270 (2.3%) had GIB (P < 0.001). GIB was seen in 3/552 patients taking rivaroxaban (0.5%, P = 0.024). GIB was seen in 5/256 patients taking apixaban (2%), but this did not reach statistical significance. GIB was seen in 1/198 patients taking dabigatran (0.5%), but this did not reach statistical significance. Factors associated with increased risk of GI bleeding included chronic kidney disease and diabetes mellitus. Patients not on proton pump inhibitors, clopidogrel, and nonsteroidal anti-inflammatory medications had an increased risk of GIB. CONCLUSION: Given similar efficacy of DOACs to warfarin shown in prior studies, the choice of oral anticoagulant rests largely on the safety profile. In a population of patients seen in the VA AC clinic, the most commonly prescribed anticoagulant was warfarin. The risk of GI bleeding was highest in these patients, similar to findings in previous studies. The lowest risk was seen with dabigatran. A data set with more GIB patients would allow multiple logistic regression analysis of the medications and comorbidities identified as risk factors.