Balancing act: medicine vial and heart tangled in red threads.

Decoding Bleeding Risks: Can These Scores Really Predict Warfarin Complications?

Nico Varela in Health & Wellness December 2025 • 4 min read.

"Unraveling the complexities of bleeding risk scores for heart disease patients on warfarin – what you need to know to stay safe."

Warfarin, a widely prescribed anticoagulant, plays a crucial role in preventing dangerous blood clots in individuals with heart conditions. However, this life-saving medication comes with a significant risk: bleeding. Balancing the benefits of clot prevention against the potential for hemorrhage is a challenge that doctors and patients face daily.

To navigate this delicate balance, clinicians often rely on bleeding risk scores – tools designed to predict a patient's likelihood of experiencing a bleeding event while on warfarin. These scores incorporate various factors, such as age, medical history, and concurrent medications, to estimate risk. But how reliable are these scores, especially across diverse populations?

A recent study published in PLOS ONE has investigated the predictive ability of several commonly used bleeding risk scores in a group of Brazilian outpatients with heart disease taking warfarin. The findings shed light on the limitations of these scores and highlight the need for more accurate and tailored risk assessment strategies.

Bleeding Risk Scores: Do They Really Work?

Balancing act: medicine vial and heart tangled in red threads.

The study, led by João Antonio de Queiroz Oliveira and colleagues, aimed to evaluate the performance of nine different bleeding risk prediction models in a cohort of 280 heart disease outpatients in Brazil. These models included well-known scores such as OBRI, Kuijer, Kearon, HEMORR2HAGES, Shireman, RIETE, HAS-BLED, ATRIA, and ORBIT.

Researchers collected data on major bleeding events, clinically relevant non-major bleeding, and non-major bleeding episodes occurring within a 12-month follow-up period. They then assessed how well each prediction model could discriminate between patients who experienced bleeding events and those who did not, using statistical measures such as Nagelkerke's R², concordance (c) statistic, and Hosmer-Lemeshow goodness-of-fit statistic.

Major Bleeding: Significant hemorrhages requiring hospitalization, blood transfusions, or causing substantial drops in hemoglobin levels.
Clinically Relevant Non-Major Bleeding: Bleeding events requiring medical intervention but not meeting the criteria for major bleeding.
Non-Major Bleeding: Minor bleeding episodes not requiring medical intervention.

The study revealed that most of the prediction models had limited ability to accurately predict bleeding risk in this population. Only two models, Shireman et al. and ORBIT, demonstrated acceptable performance in predicting major bleeding, while the others showed poor discriminative ability. Furthermore, all models exhibited low overall performance and struggled to predict clinically relevant non-major and non-major bleeding events.

What Does This Mean for Warfarin Users?

The study underscores the importance of individualized risk assessment when prescribing and managing warfarin therapy. While bleeding risk scores can provide some guidance, they should not be solely relied upon to determine a patient's risk. Factors such as patient-specific characteristics, comorbidities, and lifestyle considerations should also be taken into account.

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This article is based on research published under:

DOI-LINK: 10.1371/journal.pone.0205970, Alternate LINK

Title: Predictive Ability Of Scores For Bleeding Risk In Heart Disease Outpatients On Warfarin In Brazil

Subject: Multidisciplinary

Journal: PLOS ONE

Publisher: Public Library of Science (PLoS)

Authors: João Antonio De Queiroz Oliveira, Antonio Luiz Pinho Ribeiro, Daniel Dias Ribeiro, Vandack Nobre, Manoel Otávio Da Costa Rocha, Maria Auxiliadora Parreiras Martins

Published: 2018-10-19

Everything You Need To Know

What is Warfarin and why is it associated with bleeding risks?

Warfarin is an anticoagulant, a medication used to prevent dangerous blood clots in individuals with heart conditions. While effective, Warfarin carries a significant risk of bleeding. This is because the drug thins the blood, making it less able to clot. Therefore, any injury or underlying medical condition can lead to excessive bleeding. The challenge for both doctors and patients is to balance the benefits of preventing clots against the potential harm caused by hemorrhage.

What are bleeding risk scores and how are they used in managing Warfarin therapy?

Bleeding risk scores are tools designed to predict a patient's likelihood of experiencing a bleeding event while taking Warfarin. These scores incorporate various factors such as age, medical history, and concurrent medications. Clinicians use these scores to assess a patient's risk of bleeding, aiding them in making informed decisions about Warfarin dosage and overall management. However, it's important to remember that these scores are just one piece of the puzzle, and should not be the only factor considered.

Which bleeding risk scores were evaluated in the study involving Brazilian outpatients, and what were the key findings?

The study, led by João Antonio de Queiroz Oliveira and colleagues, evaluated the performance of nine different bleeding risk prediction models. These models included OBRI, Kuijer, Kearon, HEMORR2HAGES, Shireman, RIETE, HAS-BLED, ATRIA, and ORBIT. The key findings revealed that most prediction models demonstrated limited ability to accurately predict bleeding risk in this population. Only Shireman et al. and ORBIT showed acceptable performance in predicting major bleeding, while the others showed poor discriminative ability and struggled to predict non-major bleeding events.

What are the different types of bleeding events considered in the context of Warfarin therapy and the study?

The study categorized bleeding events into three main types: Major Bleeding, Clinically Relevant Non-Major Bleeding, and Non-Major Bleeding. Major Bleeding events are significant hemorrhages requiring hospitalization or blood transfusions, or causing substantial drops in hemoglobin levels. Clinically Relevant Non-Major Bleeding requires medical intervention but doesn't meet the criteria for major bleeding. Non-Major Bleeding refers to minor bleeding episodes not requiring medical intervention. Understanding these distinctions helps in assessing the severity and impact of bleeding risks associated with Warfarin use.

Based on the study's findings, what are the implications for Warfarin users and their healthcare providers?

The study emphasizes the importance of individualized risk assessment when prescribing and managing Warfarin therapy. The results suggest that while bleeding risk scores can provide some guidance, they shouldn't be solely relied upon to determine a patient's risk. Patient-specific characteristics, comorbidities, and lifestyle considerations should also be taken into account. Healthcare providers need to consider multiple factors beyond the scores to provide optimal and personalized care. Warfarin users should actively communicate with their healthcare providers to discuss their individual risk factors and management strategies.