Abstract: Objective To analyze the risk factors of over-anticoagulation with warfarin in the elderly patients with valvular atrial fibrillation. Methods A total of 235 elderly patients with valvular atrial fibrillation who were treated with warfarin from March 2022 to May 2024 were selected. According to the international standardized ratio (INR) after 7 days of treatment, the patients were divided into over-anticoagulation group and normal anticoagulation group. The clinical data of the two groups were compared, and the risk factors of over-anticoagulation in the elderly patients with valvular atrial fibrillation were analyzed. The predictive value of the risk factors for over-anticoagulation was analyzed. Results Among 235 patients, the incidence rate of over-anticoagulation was 22.98% (54/235). The proportion of the patients aged 80 years or older, combined with hypoproteinemia, and combined with amiodarone, the number of combined medication, the levels of creatinine and aspartate aminotransferase (AST), and initial warfarin dose at admission in the over-anticoagulation group were higher than those in the normal anticoagulation group, and the level of alanine aminotransferase (ALT), the body mass and the proportion of diabetes mellitus were lower than those in the normal anticoagulation group (P<0.05). Logistic regression analysis showed that age ≥80 years (OR=3.991, 95%CI: 1.754-9.078), the level of AST at admission (OR=4.764, 95%CI: 2.094-10.836), the number of combination medication (OR=4.170, 95%CI: 1.833-9.487) were independent risk factors, and body mass (OR=0.277, 95%CI: 0.122-0.630) was the protective factor for over-anticoagulation in the elderly patients with valvular atrial fibrillation. The area under the receiver operating characteristic curve of age ≥80 years, AST at admission, the number of combined medication, body mass and combined model in predicting over-anticoagulation was 0.656, 0.885, 0.792, 0.691 and 0.978, respectively (P<0.05). Conclusions The elderly patients with valvular atrial fibrillation who have older age, higher AST level at admission, higher number of combined medication, and lower body mass have a higher risk of over-anticoagulation with warfarin. The development of targeted management strategies can help to reduce the risk of over-anticoagulation in the elderly patients with valvular atrial fibrillation.

Key words: aged, valvular atrial fibrillation, warfarin, over-anticoagulation, risk factors