Quality of anticoagulation with the use of warfarin in long-term care in a tertiary care hospital using time spent in therapeutic range as a predictive parameter

Abstract

Background: Warfarin was a frequently prescribed long-term anticoagulant before the advent of novel oral anticoagulants or direct oral anticoagulants. These drugs are used for the primary or secondary prevention of stroke in patients with atrial fibrillation or for the treatment and prophylactic prevention of venous thromboembolism. This study aimed to assess the anticoagulation control of patients receiving warfarin at a tertiary care hospital. Methods: This retrospective cohort study was conducted in an anticoagulation clinic at a tertiary care hospital in Saudi Arabia and included 113 patients who had been treated with warfarin for at least 3 months. Thereafter, the international normalized ratio results were collected for 3 years. Anticoagulation control was assessed by calculating time within the therapeutic range (TTR) as per the Rosendaal method. Results: A total of 113 patients (mean age, 56 ± 17.6 years; 64.6% of females) were included. The mean TTR was 48.1%. Almost one-third of the patients (31.3%) had poor anticoagulation control defined as a TTR of <50%. Poor anticoagulation control was significantly associated with a higher CHADS2 (congestive heart failure, hypertension, age, diabetes, and stroke/transient ischemic attack) score (P = 0.043). TTR did not differ significantly between men and women, and it was not associated with age or anticoagulation therapy duration. Conclusion: Anticoagulation quality was suboptimal in patients receiving warfarin in a tertiary care hospital, with nearly 41% of time spent outside the therapeutic range. Methods should be implemented to improve anticoagulation control in appropriate patient groups.

Keywords

• anticoagulation
• international normalized ratio
• time within the therapeutic range
• warfarin