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ORBIT Score Predicts Bleeding Risk in AF Patients


NEW YORK - The five-factor ORBIT bleeding score accurately predicts major bleeding risk in patients with atrial fibrillation (AF) who are taking oral anticoagulants (OACs), researchers report.

"The ORBIT score highlights modifiable factors that increase bleeding risk and can help providers identify high-risk AF patients for closer monitoring," Dr. Emily C. O'Brien, from Duke Clinical Research Institute, Durham, North Carolina, said by email. "Along with clinical judgment, the ORBIT score can be used to give an estimate of bleeding risk for any AF patient considering OAC treatment."

Two existing bleeding scores - HAS-BLED and ATRIA - are based on small numbers of events and have shown inconsistent performance. They also may require elements that are not available for all OAC users, the researchers wrote.

Dr. O'Brien's team developed a five-element bleeding score and compared its performance with those of HAS-BLED and ATRIA using data from the ORBIT-AF and ROCKET-AF studies.

The numerical score included the five strongest predictors of bleeding:

-Older age (75 years and above): one point

-Reduced hemoglobin, hematocrit, or history of anemia: two points

-Bleeding history: two points

-Insufficient kidney function (eGFR below 60 mL/min/1.73 m2): one point

-Treatment with an antiplatelet agent: one point

Observed bleeding rates in the ORBIT-AF participants increased with increasing ORBIT bleeding score: from 2.4 per 100 patient-years in the low-risk group (scores 0-2) to 4.7 per 100 patient-years in the medium-risk group (score 3) to 8.1 per 100 patient-years in the high-risk group (scores 4-7), according to the Sept. 30 European Heart Journal online report.

In both the ORBIT-AF and ROCKET-AF cohorts, the ORBIT bleeding score showed better discrimination than the HAS-BLED and ATRIA scores.

Model calibration analysis also showed superior calibration for the ORBIT bleeding score. The HAS-BLED score showed relatively poor calibration for low-risk score strata, whereas the ATRIA score showed poor calibration for most risk groups.

"The ORBIT score is a simple, useful tool that predicts bleeding as well as other, more complicated scores and can be used in any AF patient regardless of the type of OAC he or she is taking," Dr. O'Brien said.

"For chronic conditions like AF, periodic assessment of risk for adverse events is important to support clinical decision-making," Dr. O'Brien explained. "Risk factors may

change over time particularly as patients get older. Therefore, incorporating new data on these factors into longitudinal risk assessment provides an optimal framework for ongoing AF management."

"While bleeding risk estimation can be helpful in identifying high-risk AF patients for closer monitoring, it is important to note that prior work has demonstrated a net clinical benefit of OAC even in patients with high estimated bleeding risk," the researchers wrote. "Further, while risk scores provide important information to the clinician for estimating risk of adverse events, they represent only one consideration relevant to therapeutic decision making."

Janssen Scientific Affairs sponsors ORBIT-AF; the Agency for Healthcare Research and Quality partially supported this research. Ten coauthors reported relevant relationships.

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