Evidence map›Paper›PMID 41068845›Full record

ArticleThrombosis journal2025

A simple formula for predicting the warfarin dose in atrial fibrillation: development, external validation, and model comparison.

Anunya Ujjin, Natnicha Pongbangli, Wanwarang Wongcharoen, Arisara Suwanagool, Chatree Chai-Adisaksopha

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Article in Thrombosis journal, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

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5 authors.

Anunya UjjinDivision of Medicine, Neurological Institute of Thailand, Bangkok, Thailand.
Natnicha PongbangliDivision of Cardiology, Department of Internal Medicine, Chiang Rai Prachanukroh Hospital, Chiang Rai, Thailand.
Wanwarang WongcharoenDivision of Cardiology, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Arisara SuwanagoolDivision of Cardiology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Chatree Chai-AdisaksophaDepartment of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. Chatree.chai@cmu.ac.th.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundThe dose of warfarin varies between individuals. Several formulas for predicting the maintenance dose of warfarin have been developed; however, most are complicated and not practical for clinical use.

objectiveTo determine factors that predict warfarin dosage and the relationship between clinical variables and the maintenance dose of warfarin, and to develop a simple formula for predicting the maintenance dose of warfarin that is particularly useful for identifying patients with atrial fibrillation (AF) who are at higher risk of bleeding, without relying on pharmacogenetic data. MATERIALS AND

methodsThis was a retrospective cohort study carried out between 2011 and 2021. All patients are started on warfarin with a target INR of 2.0 to 3.0. The prediction models for the maintenance dose were developed using a first-order equation. Correlation and performance of the formula were examined in training and validation cohorts.

resultsA training cohort consisted of 520 patients with a mean age of 69 ± 12 years. The proposed warfarin dosing formula was 3+(0.02×body weight (kg))-(0.02×age (years))-(0.4×serum creatinine (mg/dL)).When compared with a warfarin dosing formula, a 3-mg dose was associated with overdosing with an odds ratio [OR] of 3.31 (95%CI 2.26-4.84, p < 0.0001) in patients whose body weight was < 60 kg, OR 3.08 (95%CI 2.15-4.40, p < 0.0001) in patients aged ≥ 70 years and OR 2.39 (95% CI 1.67-3.44, p < 0.0001) in patients with eGFR < 50 mL/min. The findings in the validation cohort of 632 patients were concordant with the training cohort.

conclusionA simple warfarin dosing formula incorporating age, body weight, and serum creatinine reduced the risk of warfarin overdose in a high-risk population.

Indexed as

Atrial fibrillationFormulaWarfarin

Identifiers

PMID41068845
PMCPMC12512375

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