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Oral anticoagulants in the elderly

2003; Wiley; Volume: 120; Issue: 3 Linguagem: Inglês

10.1046/j.1365-2141.2003.04110.x

1365-2141

Paul Froom, Ehud Miron, Mira Barak,

Venous Thromboembolism Diagnosis and Management

Summary. Over a 1‐year period, 34 998 prothrombin time tests were performed on 2379 patients aged 40–89 years with a recommended target International Normalized Ratio (INR) value of 2·5. At least one INR value of ≥ 5 was found in 507/2379 patients (21·3%). The elderly demonstrated higher maximum and lower minimum INR values, lower warfarin doses, and an increased number of tests performed. After adjustment for these factors, the risk of INR values ≥ 5 increased with age by 15% every 10 years (95% CI 4–28%). We conclude that age is a risk factor for more unstable prothrombin time results.