Study of INR Profile in Patients on Vitamin K Antagonists in Tanta University Hospital Egypt

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Dina M. AL- Ibshehy
Mahmoud A. Abouomar
Enas E. Draz
Magdy M. EL- Masry


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.

Oral anticoagulant, INR, TTR.

Article Details

How to Cite
Ibshehy, D. M. A.-, Abouomar, M. A., Draz, E. E., & Masry, M. M. E.-. (2020). Study of INR Profile in Patients on Vitamin K Antagonists in Tanta University Hospital Egypt. Cardiology and Angiology: An International Journal, 9(4), 47-56.
Original Research Article


Raskob G, Angchaisuksiri P, Blanco A, et al. ISTH steering committee for world thrombosis day. Thrombosis: A major contributor to global disease burden. Arterioscler Thromb Vasc Biol. 2014; 34(11):2363 -71.

Raskob GE, Silverstein R, Bratzler DW, et al. Surveillance for deep vein thrombosis and pulmonary embolism: Recommendations from a national workshop. American journal of preventive medicine. 2010;38(4):S502-S9.

Baglin T, Hillarp A, Tripodi A, et al. Measuring oral direct inhibitors of thrombin and factor Xa: A recommendation from the subcommittee on control of anticoagulation of the scientific and standardization committee of the international society on thrombosis and haemostasis. Journal of Thrombosis and Haemostasis. 2013;11(4): 756-60.

Schellack N, Esterhuizen H. Understanding anticoagulation therapy for stroke prevention and atrial fibrillation. SA Pharmaceutical Journal. 2013;80(7):13- 9.

Guimarães PO, Lopes RD, Alexander JH, et al. International normalized ratio control and subsequent clinical outcomes in patients with atrial fibrillation using warfarin. Journal of thrombosis and thrombolysis. 2019;48(1):27-34.

Njovane X, Fasinu P. Comparative utilization of warfarin in two PHCs in Cape Town. Cardiovascular J Afr. 2012;23:901-4.

Comino N, Cottrell WN, Mortimer C. Automatic drug use audit in primary care: A pilot evaluation of warfarin use for patients with atrial fibrillation. Australian family physician. 2005;34(9):798.

Buchanan E. Guideline for prophylactic anticoagulation. S Afr Med J. 2004;94:691-5.

Policy AfHC, Research. Life‐saving treatments to prevent stroke underused. Research Activities. 1995;187:1-2.

Nasser S, Cecchele R, Touma S, et al. Documentation of warfarin education provided to hospital patients: A clinical audit. Journal of Pharmacy Practice and Research. 2012;42(2):129-33.

Sonuga BO, Hellenberg DA, Cupido CS, et al. Profile and anticoagulation outcomes of patients on warfarin therapy in an urban hospital in Cape Town, South Africa. African Journal of Primary Health Care & Family Medicine. 2016;8(1):1-8.

Szummer K, Gasparini A, Eliasson S, et al. Time in therapeutic range and outcomes after warfarin initiation in newly diagnosed atrial fibrillation patients with renal dysfunction. Journal of the American Heart Association. 2017;6(3):e004925.

Anderson JL, Horne BD, Stevens SM, et al., editors. A double-blind, randomized trial of genotype guided versus standard warfarin dosing in patients initiated on oral anticoagulation: The Couma-gen study. circulation; Lippincott Williams & Wilkins 530 Walnut St, Philadelphia, Pa 19106-3621 USA; 2007.

Rudasill SE, Liu J, Kamath AF. Revisiting the international normalized ratio (INR) threshold for complications in primary Total knee arthroplasty: an analysis of 21,239 cases. JBJS. 2019;101(6):514-22.

Wieland E, Shipkova M. Pharmacokinetic and pharmacodynamic drug monitoring of direct-acting oral anticoagulants: Where do we stand? Therapeutic drug monitoring. 2019;41(2):180-91.

Schmitt L, Speckman J, Ansell J. Quality assessment of anticoagulation dose management: Comparative evaluation of measures of time-in-therapeutic range. Journal of thrombosis and thrombolysis. 2003;15(3):213-6.

Rosendaal F, Cannegieter S, Van der Meer F, et al. A method to determine the optimal intensity of oral anticoagulant therapy. Thrombosis and haemostasis. 1993;70(03):236-9.

Wallentin L, Yusuf S, Ezekowitz MD, et al. Efficacy and safety of dabigatran compared with warfarin at different levels of international normalised ratio control for stroke prevention in atrial fibrillation: an analysis of the RE-LY trial. The Lancet. 2010;376(9745):975-83.

Macedo AF, Bell J, McCarron C, et al. Determinants of oral anticoagulation control in new warfarin patients: Analysis using data from clinical practice research datalink. Thrombosis research. 2015; 136(2):250-60.

Witt DM, Delate T, Clark NP, et al. Outcomes and predictors of very stable INR control during chronic anticoagulation therapy. Blood, The Journal of the American Society of Hematology. 2009; 114(5):952-6.

Farsad B-F, Abbasinazari M, Dabagh A, et al. Evaluation of time in therapeutic range (TTR) in patients with nonvalvular atrial fibrillation receiving treatment with warfarin in Tehran, Iran: A cross-sectional study. Journal of clinical and diagnostic research: JCDR. 2016;10(9):FC04.

Hong K-S, Kim Y-K, Bae H-J, et al. Quality of anticoagulation with warfarin in Korean patients with atrial fibrillation and prior stroke: A multicenter retrospective observational study. Journal of Clinical Neurology.2017;13(3):273-80.

Dlott JS, George RA, Huang X, et al. National assessment of warfarin anticoagulation therapy for stroke prevention in atrial fibrillation. Circulation. 2014;129(13):1407-14.

Apostolakis S, Sullivan RM, Olshansky B, et al. Factors affecting quality of anticoagulation control among patients with atrial fibrillation on warfarin: The SAMe-TT2R2 score. Chest. 2013;144(5): 1555-63.

Boulanger L, Kim J, Friedman M, et al. Patterns of use of antithrombotic therapy and quality of anticoagulation among patients with non‐valvular atrial fibrillation in clinical practice. International Journal of Clinical Practice. 2006;60(3):258-64.

Nelson WW, Desai S, Damaraju CV, et al. International normalized ratio stability in warfarin-experienced patients with nonvalvular atrial fibrillation. American Journal of Cardiovascular Drugs. 2015; 15(3):205-11.

Fang MC, Stafford RS, Ruskin JN, et al. National trends in antiarrhythmic and antithrombotic medication use in atrial fibrillation. Archives of Internal Medicine. 2004;164(1):55-60.

Taibanguay N, Chaiamnuay S, Asavatanabodee P, et al. Effect of patient education on medication adherence of patients with rheumatoid arthritis: a randomized controlled trial. Patient Preference and Adherence. 2019;13:119.

Björck F, Kadhim H, Själander A. Predictors for INR-control in a well-managed warfarin treatment setting. Journal of Thrombosis and Thrombolysis. 2019;47(2):227-32.

Efird LM, Mishkin DS, Berlowitz DR, Ash AS, Hylek EM, Ozonoff A, et al. Stratifying the risks of oral anticoagulation in patients with liver disease. Circulation: Cardiovascular Quality and Outcomes. 2014;7(3):461-7.

Nathisuwan S, Dilokthornsakul P, Chaiyakunapruk N, et al. Assessing evidence of interaction between smoking and warfarin: A systematic review and meta-analysis. Chest. 2011;139(5):1130-9.

Holbrook AM, Pereira JA, Labiris R, et al. Systematic overview of warfarin and its drug and food interactions. Archives of Internal Medicine. 2005;165(10):1095- 106.

Schein JR, White CM, Nelson WW, et al. Vitamin K antagonist use: Evidence of the difficulty of achieving and maintaining target INR range and subsequent consequences. Thrombosis Journal. 2016; 14(1):14.