International Journal of Clinical Pharmacy

, Volume 39, Issue 1, pp 41–44 | Cite as

Improvement of time in therapeutic range with warfarin by pharmaceutical intervention

  • Alvaro Víquez-Jaikel
  • Victoria Hall-Ramírez
  • Allan Ramos-EsquivelEmail author
Short Research Report


Background Anticoagulation therapy with warfarin is highly effective for prevention and treatment of thromboembolic disorders. Nevertheless, its management is challenging especially in developing countries, where the medical access is difficult and patient education is poor. Objective To determine the effect of pharmaceutical intervention (PI) on the time in therapeutic range (TTR) of a group of anticoagulated patients from our referral center. Method A group of consecutive outpatients previously treated by usual medical care underwent PI. The intervention consisted in the identification and avoidance of food and drug interactions, the confection of medication schedule charts and education to patients regarding side effects and drug monitoring. Mean TTR before and after PI was compared through the Wilcoxon test for repeated measures. Regression analyses were performed to assess the relationship between a TTR level under 65% and potential explanatory variables. Results Mean TTR before PI was 37.4 ± 23.5% and after PI it raised to 67.0 ± 24.9%. Mean change in TTR was +29.5% (95% CI 14.5–44.6; p < 0.001). Before PI only 4 patients had TTR values above 65%, in contrast to 18 patients after PI. Conclusion Our findings support the efficacy of PI to improve TTR values in patients treated with warfarin.


Anticoagulants Costa Rica Drug monitoring International normalized ratio Pharmaceutical intervention Warfarin 



No specific funding was received for this project.

Conflicts of interest

The authors have no conflict of interest with regard to this publication.

Supplementary material

11096_2016_403_MOESM1_ESM.docx (17 kb)
Supplementary material 1 (DOCX 17 kb)


  1. 1.
    Kaatz S. Determinants and measures of quality in oral anticoagulation therapy. J Thromb Thrombolysis. 2008;25:61–6.CrossRefPubMedGoogle Scholar
  2. 2.
    Wan Y, Heneghan C, Perera R, Roberts N, Hollowell J, Glasziuou P, et al. Anticoagulation control and prediction of adverse events in patients with atrial fibrillation. Circ Cardiovasc Qual Outcomes. 2008;1:84–91.CrossRefPubMedGoogle Scholar
  3. 3.
    Mearns ES, Kohn CG, Song JS, Hawthorne J, Meng J, White CM, et al. Meta-analysis to assess the quality of international normalized ratio control and associated outcomes in venous thromboembolism patients. Thromb Res. 2014;134:310–9.CrossRefPubMedGoogle Scholar
  4. 4.
    Motycka C, Kesgen C, Smith S, Alvarez E, Jones K. Potential benefits of warfarin monitoring by a clinical pharmacist in a long term care facility. J Thromb Thrombolysis. 2012;33:173–7.CrossRefPubMedGoogle Scholar
  5. 5.
    Young S, Bishop L, Twells L, Dillon C, Hawboldt J, O’Shea P. Comparison of pharmacist managed anticoagulation with usual medical care in a family medicine clinic. BMC Fam Pract. 2011;12:88.CrossRefPubMedPubMedCentralGoogle Scholar
  6. 6.
    Wallentin L, Yusuf S, Ezekowitz MD, Alings M, Flather M, Franzosi MG, 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. Lancet. 2010;376:975–83.CrossRefPubMedGoogle Scholar
  7. 7.
    Connolly SJ, Pogue J, Eikelboom J, Flaker G, Commerford P, Franzosi MG, et al. Benefit of oral anticoagulant over antiplatelet therapy in atrial fibrillation depends on the quality of international normalized ratio control achieved by centers and countries as measured by time in therapeutic range. Circulation. 2008;118:2029–37.CrossRefPubMedGoogle Scholar
  8. 8.
    Holbrook A, Schulman S, Witt DM, Vandvik PO, Fish J, Kovacs MJ, et al. Evidence-based management of anticoagulant therapy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141:e152S–84S.CrossRefPubMedPubMedCentralGoogle Scholar
  9. 9.
    Rosendaal FR, Cannegieter SC, van der Meer FJ, Briët E. A method to determine the optimal intensity of oral anticoagulant therapy. Thromb Haemost. 1993;69:236–9.PubMedGoogle Scholar
  10. 10.
    Singer DE, Hellkamp AS, Piccini JP, Mahaffey KW, Lokhnygina Y, Pan G, et al. Impact of global geographic region on time in therapeutic range on warfarin anticoagulant therapy: data from the ROCKET AF clinical trial. J Am Heart Assoc. 2013;2:e000067.PubMedPubMedCentralGoogle Scholar

Copyright information

© Springer International Publishing 2016

Authors and Affiliations

  1. 1.Unidad de Atención FarmacéuticaHospital San Juan de Dios, Caja Costarricense de Seguro SocialSan JoséCosta Rica
  2. 2.Farmacia HospitalariaUniversidad Autónoma de Ciencias MédicasSan JoséCosta Rica
  3. 3.Centro de Información de Medicamentos, Escuela de FarmaciaUniversidad de Costa RicaSan JoséCosta Rica
  4. 4.Departamento de Farmacología, Escuela de MedicinaUniversidad de Costa RicaSan JoséCosta Rica

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