In 2010, the blood thinner dabigatran (brand name Pradaxa) was approved by the U.S. Food and Drug Administration as a treatment option for people with atrial fibrillation. Dabigatran was at least as effective as warfarin, had fewer bleeding-related side effects, and was easier to use, not needing regular blood tests and not affected by food. Studies on the use of dabigatran were carried out after the drug's approval and results since then, however, have been dismal.
A study done by researchers from the University of Pittsburgh analyzed medical and pharmacy claims from 9,400 randomly chosen individuals with atrial fibrillation but not with damaged heart valves and have healthcare coverage under Medicare. In the group, 1,300 were given dabigatran while 8,100 were prescribed warfarin within 60 days of being diagnosed with atrial fibrillation. Researchers followed all participants until December 2011 or until the men and women died, stopped using their medication, or switched to a different blood thinner.
The group given dabigatran had 9 percent reporting major bleeding while the same only happened to the group prescribed warfarin in 6 percent of the cases. For both groups, bleeding sites varied. Most of those who reported bleeding while on dabigatran experienced stomach bleeding while those on warfarin had slightly higher instances of head bleeding. Additionally, blacks and those suffering from chronic kidney disease were likelier to bleed when using dabigatran. All these results were published in the journal JAMA Internal Medicine.
Before dabigatran, the best way to treat atrial fibrillation and prevent a stroke was to take warfarin. Unfortunately, warfarin was complicated to use, easily affected by the food a patient eats and needing frequent tests to ensure there is neither too much nor too little of the medication in the blood.
After dabigatran, two other drugs to thin the blood were approved: apixaban and rivaroxaban. Like dabigatran, they were easier to use than warfarin, although all three were more expensive. Studies are still being done on apixaban and rivaroxaban to test for real-world safety but so far long-term side effects for the medications, including dabigatran, have not been established.
Although it takes a lot more work to use, warfarin is still the primary choice for doctors when starting patients on atrial fibrillation treatment. Only when frequent blood tests are impossible to do or a patient has a higher-than-normal risk of bleeding are dabigatran, apixaban, and rivaroxaban prescribed.
Researchers from the University of Pittsburgh included: Inmaculada Hernandez, PharmD; Antonio Piñera, MD; Seo Hyon Baik, PhD; and Yuting Zhang, PhD.
