Vitamin K Antagonist Use and Level of Anticoagulation Control Among Patients at a Tertiary Hospital in Northern Tanzania

Background Vitamin K antagonists (VKA) continue to be the principal anticoagulants for both the treatment and prevention of venous thromboembolism. The use of VKA often requires regular monitoring to avoid over-anticoagulation and prevent thromboembolic complications. The aim was to determine the in...

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Main Authors: Sarah K. Gharib MMed, Abid M. Sadiq MMed, Faryal M. Raza MMed, Sophia S. Muhali MMed, Annette A. Marandu MMed, Norman J. Kyala MMed, Eliasa K. Ndale MMed, Venance P. Maro MMed, William P. Howlett PhD, Elifuraha W. Mkwizu MMed, Nyasatu G. Chamba PhD, Furaha S. Lyamuya MMed, Elichilia R. Shao MMed, Kajiru G. Kilonzo MPhil
Format: Article
Language:English
Published: SAGE Publishing 2025-01-01
Series:Journal of Cardiovascular Pharmacology and Therapeutics
Online Access:https://doi.org/10.1177/10742484251315104
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Summary:Background Vitamin K antagonists (VKA) continue to be the principal anticoagulants for both the treatment and prevention of venous thromboembolism. The use of VKA often requires regular monitoring to avoid over-anticoagulation and prevent thromboembolic complications. The aim was to determine the indication for VKA use and factors associated with suboptimal anticoagulation control among patients in northern Tanzania. Methods This was a retrospective cohort study that examined the anticoagulation data of patients on long-term VKA from 1 st January 2020 to 31 st December 2022. Eligible participants were those on VKAs for at least 7 days and with at least 3 international normalized ratio (INR) results. The level of anticoagulation control was determined through the calculation of the time-in-therapeutic range (TiTR) using the Rosendaal and the percent of INR in therapeutic range methods. Results TiTR was found to be 17% using the direct method and 16% using the Rosendaal formula. 102 tests out of 365 were within the target range (28%). Absence of health insurance (aRR: 1.24, 95% CI: 1.06-1.44, P  = .007), alcohol consumption (aRR: 1.37, 95% CI: 1.15-1.62, P  < .001), and prolonged intervals between tests of 14 to 28 days (aRR: 1.34, 95% CI: 1.05-1.74, P  = .018) showed association with INR being out of range. Conclusion Patients who achieved target therapeutic anticoagulation control were less than the acceptable 65%. Anticoagulation outcomes were better in patients with frequent INR monitoring and those with health insurance. Alcohol consumption carries a high risk of poor anticoagulation control. Further studies are needed to enforce better INR control.
ISSN:1940-4034