Warfarin is associated with higher rates of upper gastrointestinal bleeding but not overall or lower GI bleeding rates, compared with direct oral anticoagulants (DOACs), according to a new nationwide report from Iceland.
In addition, warfarin is associated with higher rates of major GI bleeding, compared with apixaban.
“Although there has been a myriad of studies comparing GI bleeding rates between warfarin and DOACs, very few studies have compared upper and lower GI bleeding rates specifically,” Arnar Ingason, MD, PhD, a gastroenterology resident at the University of Iceland and Landspitali University Hospital, Reykjavik, said in an interview.
“Knowing whether the risk of upper and lower GI bleeding differs between warfarin and DOACs is important, as it can help guide oral anticoagulant selection,” he said.
“Given that warfarin was associated with higher rates of upper GI bleeding compared to DOACs in our study, warfarin may not be optimal for patients with high risk of upper GI bleeding, such as patients with previous history of upper GI bleeding,” Dr. Ingason added.
The study was published online in Clinical Gastroenterology and Hepatology.
Analyzing bleed rates
Dr. Ingason and colleagues analyzed data from electronic medical records for more than 7,000 patients in Iceland who began a prescription for oral anticoagulants between 2014 and 2019. They used inverse probability weighting to yield balanced study groups and calculate the rates of overall, major, upper, and lower GI bleeding. All events of gastrointestinal bleeding were manually confirmed by chart review.
Clinically relevant GI bleeding was defined as bleeding that led to medical intervention, unscheduled physician contact, or temporary cessation of treatment. Upper GI bleeding was defined as hematemesis or a confirmed upper GI bleed site on endoscopy, whereas lower gastrointestinal bleeding was defined as hematochezia or a confirmed lower GI bleed site on endoscopy. Patients with melena and uncertain bleeding site on endoscopy were classified as having a gastrointestinal bleed of unknown location.
Major bleeding was defined as a drop in hemoglobin of at least 20 g/L, transfusion of two or more packs of red blood cells, or bleeding into a closed compartment such as the retroperitoneum.
In total, 295 gastrointestinal bleed events were identified, with 150 events (51%) classified as lower, 105 events (36%) classified as upper, and 40 events (14%) of an unknown location. About 71% required hospitalization, and 63% met the criteria for major bleeding. Five patients died, including three taking warfarin and the other two taking apixaban and rivaroxaban.
Overall, warfarin was associated with double the rate of upper GI bleeding, with 1.7 events per 100 person-years, compared with 0.8 events per 100 person-years for DOACs. The rates of lower GI bleeding were similar for the drugs.
Specifically, warfarin was associated with nearly 5.5 times higher rates of upper gastrointestinal bleeding, compared with dabigatran (Pradaxa, Boehringer Ingelheim), 2.6 times higher than apixaban (Eliquis, Bristol-Myers Squibb), and 1.7 times higher than rivaroxaban (Xarelto, Janssen). The risk for upper GI bleeding also was higher in men taking warfarin.
Warfarin was associated with higher rates of major bleeding, compared with apixaban, with 2.3 events per 100 person-years versus 1.5 events per 100 person-years. Otherwise, overall and major bleed rates were similar for users of warfarin and DOACs.
“GI bleeding among cardiac patients on anticoagulants and antiplatelets is the fastest growing group of GI bleeders,” Neena Abraham, MD, professor of medicine and a gastroenterologist at the Mayo Clinic in Scottsdale, Ariz., said in an interview.
Dr. Abraham, who wasn’t involved with this study, runs a dedicated cardiogastroenterology practice and has studied these patients’ bleeding risk for 20 years.
“This is a group that is ever increasing with aging baby boomers,” she said. “It is anticipated by 2040 that more than 40% of the U.S. adult population will have one or more cardiovascular conditions requiring the chronic prescription of anticoagulant or antiplatelet drugs.”