What's My Risk of Bleeding Caused by My Blood Thinner?
Answers
In a 1998 study, the risk of bleeding when on a blood thinner such as warfarin (often used to help treat atrial fibrillation) was found to go up with the following factors:
Age 65 or older
History of stroke
History of bleeding from the stomach or bowel
One or more of the following conditions:
Recent heart attack
Moderate or severe anemia (hematocrit less than 30 percent)
Chronic kidney disease (creatinine greater than 1.5 mg/dL)
Diagnosis of diabetes
In people on warfarin for two years, of those with none of the above risk factors, 3 percent had a major bleeding event. Among those with one or two of the above risk factors, 12 percent had a major bleeding event. Among those with three or four risk factors, 53 percent had a major bleeding event.
In a more recent study, published in 2010, the risk of bleeding while on warfarin was linked to the following factors:
Uncontrolled high blood pressure (defined as having a systolic blood pressure greater than160)
Chronic kidney and/or liver problems
Prior stroke
Prior history of internal bleeding
Difficult-to-control INRs (international normalized ratios, the blood test used to monitor warfarin)
Age of 65 or older
Use of other medications that increase bleeding risk, such as aspirin and NSAIDs
Consumption of eight or more alcoholic drinks per week
Researchers found that over a year, the risk of bleeding ranged from 1.13 percent for those with no risk factors to 8.7 percent for those with four risk factors.
