For healthcare professionals
ATRIA bleeding score calculator
The ATRIA bleeding score adds points for five factors linked to major bleeding in people with atrial fibrillation (AFib) who take warfarin. This tool is written for clinicians and is not a diagnosis.
Patient details
For people with AFib on, or considering, warfarin. Nothing you enter leaves this page.
What you will see
The total ATRIA score from 0 to 10, its risk group and the points for each factor.
Educational only, not medical advice. Never start, stop or skip a blood thinner on your own.
Source
The ATRIA bleeding score by Fang MC and colleagues, Journal of the American College of Cardiology 2011 (cited, not quoted), with the items and points as printed in the open access Table 1 of Oliveira and colleagues, PLoS One 2018 (CC BY 4.0). The risk groups and major bleeding incidence are as printed in Table 2 of Sen and colleagues, Frontiers in Cardiovascular Medicine 2025 (CC BY 4.0). The tests check each item, the maximum of 10, the group edges and the age 75 edge.
Validated in
As Sen and colleagues describe it, the score was derived in a Kaiser Permanente cohort of 9,186 people with AFib on warfarin. Oliveira and colleagues note it was built from data on hospitalized patients with about 6 years of follow-up. It was built for warfarin, not for the newer direct oral anticoagulants.
Limits
Only for people with AFib, and built for warfarin. It counts bleeding risk factors; it does not estimate stroke risk or weigh the benefit of a blood thinner. Its accuracy (AUC) was 0.74 in warfarin users but 0.58 to 0.61 in studies of people on direct oral anticoagulants, as printed by Sen and colleagues. The incidence figures are group averages from the derivation cohort, not a personal prediction, and the open table does not state their time period; see the original paper for that. The renal item is printed in the open table as GFR under 30 mL/min (Oliveira and colleagues estimated it with Cockcroft-Gault creatinine clearance); the full definition is in the original paper. The anemia cut points are the ones printed by Oliveira and colleagues. Age 75 counts (75 or older); age 74 does not.
The point table
ATRIA bleeding score, as printed in Oliveira and colleagues 2018, Table 1 (Oliveira 2018) (Fang 2011):
- Anemia (hemoglobin under 12 g/dL in women, under 13 g/dL in men): 3
- Severe renal disease (GFR under 30 mL/min): 3
- Age 75 or older: 2
- Any prior bleeding: 1
- Diagnosed hypertension: 1
The maximum is 10. ATRIA stands for the Anticoagulation and Risk Factors in Atrial Fibrillation study, the cohort the score came from.
Worked example: a 78-year-old (2) with anemia (3) and diagnosed hypertension (1), normal kidney function and no past bleeding, scores 6, the high group.
Risk groups
Oliveira and colleagues print the groups as low (0 to 3 points), intermediate (4) and high (5 or more) (Oliveira 2018). Sen and colleagues print the same groups (high: 5 to 10 points) with the major bleeding incidence from the derivation cohort (Sen 2025):
- 0 to 3 points: low, major bleeding 0.8%
- 4 points: intermediate, 2.6%
- 5 to 10 points: high, 5.8%
Two items, anemia and severe renal disease, carry 3 points each, so either one together with age 75 or older already reaches the high group.
Reading the result
Sen and colleagues report an AUC of 0.74 for ATRIA in warfarin users, against 0.72 for HAS-BLED and 0.69 for HEMORR2HAGES, and lower values in people on direct oral anticoagulants (0.58 in one small study, 0.61 at 100 days in another) (Sen 2025). In the ORBIT registry, Pastori and colleagues report a c-index of 0.66 for ATRIA, close to ORBIT (0.67) and HAS-BLED (0.64), and 0.60 in the ROCKET-AF trial (Pastori 2019). In 280 Brazilian outpatients with heart disease on warfarin, Oliveira and colleagues found an AUC of 0.650 (95% CI 0.493 to 0.807) for major bleeding, and half of the 14 people with major bleeding (7) were in the low ATRIA group (Oliveira 2018).
The 2023 US atrial fibrillation guideline says that in people at high risk of stroke, bleeding risk scores should not be used on their own to decide whether to take an anticoagulant, but to find and change bleeding risk factors and to inform the decision (ACC/AHA 2023). General safety advice (not part of the score): never stop, skip or change a blood thinner because of a score. Talk to the clinician who prescribes it.
Related tools
For other bleeding scores in AFib, see the HAS-BLED score and the ORBIT bleeding score and the HEMORR2HAGES score; for stroke risk with AFib, CHA2DS2-VASc explained. To estimate kidney function first, use the creatinine clearance calculator or the eGFR calculator. Other bedside scores are listed under For healthcare professionals.
Sources
- Oliveira JAQ, Pinho Ribeiro AL, Ribeiro DD, Nobre V, Rocha MODC, Martins MAP. Predictive ability of scores for bleeding risk in heart disease outpatients on warfarin in Brazil. PLoS One. 2018;13(10):e0205970. doi:10.1371/journal.pone.0205970. PMID 30339702. Open access (CC BY 4.0). Table 1 (ATRIA items, points and risk categories), Tables 3 and 4. pmc.ncbi.nlm.nih.gov/articles/PMC6195286/
- Sen L, Kangpin X, Yihui L. Research progress on bleeding risk assessment models in anticoagulant therapy. Front Cardiovasc Med. 2025;12:1645823. doi:10.3389/fcvm.2025.1645823. PMID 41306267. Open access (CC BY 4.0). Table 2 (ATRIA risk groups, major bleeding incidence and C-statistics). pmc.ncbi.nlm.nih.gov/articles/PMC12644015/
- Fang MC, Go AS, Chang Y, Borowsky LH, Pomernacki NK, Udaltsova N, Singer DE. A new risk scheme to predict warfarin-associated hemorrhage: the ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) study. J Am Coll Cardiol. 2011;58(4):395-401. doi:10.1016/j.jacc.2011.03.031. PMID 21757117. Cited, not quoted. doi.org/10.1016/j.jacc.2011.03.031
- Pastori D, Menichelli D, Gingis R, Pignatelli P, Violi F. Tailored practical management of patients with atrial fibrillation: a risk factor-based approach. Front Cardiovasc Med. 2019;6:17. doi:10.3389/fcvm.2019.00017. PMID 30915342. Open access (CC BY 4.0). Table 1B (ORBIT items and points). pmc.ncbi.nlm.nih.gov/articles/PMC6422871/
- Joglar JA, Chung MK, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation. J Am Coll Cardiol. 2024;83(1):109-279. doi.org/10.1016/j.jacc.2023.08.017
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