CHICAGO – The ORBIT-AF bleeding risk score is a simple, user-friendly new tool for assessing the risk of major bleeding in patients with atrial fibrillation on oral anticoagulation, Emily C. O’Brien, Ph.D., announced at the American Heart Association scientific sessions.
This novel score offers significant advantages over existing bleeding risk scores, including HAS-BLED and ATRIA. Those scores were developed on the basis of small numbers of bleeding events, they show inconsistent performance, and their calculation requires data that’s often not readily accessible in busy daily practice, according to Dr. O’Brien of the Duke Clinical Research Institute in Durham, N.C.
Bruce Jancin/Frontline Medical News
Dr. Emily C. O'Brien
The new score was derived from the ORBIT-AF registry, the largest prospective U.S. registry of patients with atrial fibrillation (AF).
The score was constructed using data on 7,411 AF patients in community practice settings at 173 U.S. sites. All subjects were on oral anticoagulant therapy at baseline. During 2 years of prospective follow-up, 581 patients (7.8%) experienced a major bleeding event as defined by International Society on Thrombosis and Haemostasis criteria.
After sifting through numerous potential candidate variables, Dr. O’Brien and coinvestigators settled upon five they identified as the most potent and practical baseline predictors of major bleeding risk while on oral anticoagulation. Then they packaged them in a convenient acronym: ORBIT, for Older than 74, Renal insufficiency with an estimated glomerular filtration rate below 60 mL/minute per/1.73 m2, Bleeding history, Insufficient hemoglobin/hematocrit or anemia, and Treatment with an antiplatelet agent. The two strongest predictors – renal insufficiency and bleeding history– were awarded two points each; the others are worth one point each.
The observed major bleeding rate among patients enrolled in the ORBIT-AF registry rose with an increasing risk score. The same was true upon application of the ORBIT bleeding score to an independent study sample comprised of participants in the ROCKET-AF randomized clinical trial.
Dr. O’Brien also compared the performance of the ORBIT bleeding score to that of two existing bleeding risk scores – HAS-BLED and ATRIA – in the ORBIT-AF and ROCKET-AF cohorts. The simpler, more user friendly ORBIT bleeding score had a C-statistic of 0.67, similar to the 0.64 for HAS-BLED and 0.66 for ATRIA.
Thus, the ORBIT bleeding score is a practical new tool for use alongside the CHA2DS2-VASc stroke risk score to support clinical decision making regarding whether or not to place an individual AF patient on oral anticoagulation, Dr. O’Brien concluded.
She reported having no financial conflicts regarding this study. The ORBIT-AF registry is sponsored by Janssen.