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Background: Oral vitamin K antagonists are highly effective in the prevention and treatment of thromboembolic disease. Optimal use of these agents in clinical practice is challenged by their narrow therapeutic window. We aimed to Study the international normalized ratio values in patients on vitamin K antagonists to find out which patient characteristics that are associated with good INR control.
Methods: From June 2019 till May 2020 we studied 502 patients receiving vitamin K antagonists (VKAs) as an oral anticoagulant treatment for thromboembolic prevention for at least more than 1 month. The cases were classified into two groups according to time to therapeutic range (TTR); group I included 289 patients with TTR < 65 and group II that included 213 patients with TTR ≥ 65. We included patients with atrial fibrillation, prosthetic valve replacement or deep venous thrombosis.
Results: In univariate regression analysis, increasing age, male gender, lower level of education, diabetes mellitus, hypertension, smoking, chronic kidney disease, coronary artery disease and higher CHADS-VASC were revealed as risk factors for poor response (time to therapeutic range (TTR) < 65). With multivariate logistic regression analysis, lower level of education, HTN, smoking, CKD and higher CHADS-VASC were revealed as independent risk factors for poor response (TTR < 65).
Conclusion: This study indicated that, poor education, hypertension, smoking, chronic kidney disease, and high CHADS VSAC score were independent predictors of poor time to therapeutic range (TTC) control.
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