Analyze the impact of the degree of blood vessel aging on the anticoagulant effect and bleeding risk of warfarin. Evaluating the possibility of using the degree of blood vessel aging to guide individualized use of the anticoagulant drug warfarin.

Inclusion Criteria:

• Patients aged 65 years and older, taking warfarin, with or without premature vascular aging, regardless of gender.

  • Patients who have not concurrently or intermittently used anticoagulant drugs, including antiplatelet drugs, heparin, low molecular weight heparin, and non-vitamin K-dependent oral anticoagulants, such as dabigatran and apixaban.

    • Signing an informed consent form before blood sample collection.

Exclusion Criteria:

• Patients who are allergic to warfarin or lactose.

  • Patients who are receiving immunosuppressive agents or low molecular weight heparin anticoagulants.

    • Patients with bleeding tendencies, blood disorders with platelet counts > 400 × 10^9 /L or < 100 × 10^9 /L, hemoglobin > 169 or < 100 g/L.

      • History of peptic ulcer disease.

        • Malignant tumors, severe multi-organ dysfunction or failure such as heart, liver, and kidney.

          • Neurological disorders such as epilepsy.

Patients taking warfarin