Tara Gomes, from the University of Toronto, and colleagues conducted a population-based cohort study involving 125,195 residents of Ontario aged 66 years or older with atrial fibrillation who started taking warfarin from April 1997 through March 2008. The authors sought to examine incident hemorrhagic events.
The researchers found that the overall rate of hemorrhage was 3.8 percent per person-year. During the first 30 days of treatment the risk of major hemorrhage was highest, with a rate of 11.8 percent per person-year in all patients and 16.7 percent among those with a CHADS2 (congestive heart failure, hypertension, age ≥75 years, diabetes, prior stroke, transient ischemic attack, or thromboembolism) score of 4 or more. During the five-year follow-up period, 8.7 percent of patients had a hospital visit for hemorrhage, and of these patients, 18.1 percent died in the hospital or within seven days of discharge.