Demonstration of anticoagulation patient self-testing feasibility at an Indian Health Service facility: A case series analysis

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Ryan R. Schupbach
John M. Bousum
Michael J. Miller


Self Care, Anticoagulants, Warfarin, International Normalized Ratio, Drug Monitoring, United States


Background: Anticoagulation patient self-testing (PST) represents an alternative approach to warfarin monitoring by enabling patients to use coagulometers to test their international normalized ratio (INR) values. PST offers several advantages that potentially improve warfarin management.

Objective: To describe implementation and associated performance of a PST demonstration program at an Indian Health Service (IHS) facility.

Methods: A non-consecutive case series analysis of patients from a pharmacy-managed PST demonstration program was performed at an IHS facility in Oklahoma between July 2008 and February 2009.

Results: Mean time in therapeutic range (TTR) for the seven patients showed a small, absolute increase during the twelve weeks of PST compared to the twelve weeks prior to PST. Four of the seven patients had an increase in TTR during the twelve week course of PST compared to their baseline TTR. Three of four patients with increased TTR in the final eight week period of PST achieved a TTR of 100%. Of the three patients who experienced a decrease in TTR after initiating self-testing, two initially presented with a TTR of 100% prior to PST and one patient had a TTR of 100% for the final eight weeks of PST. The two patients not achieving a TTR of 100% during the twelve week PST period demonstrated an increase in TTR following the first four weeks of PST.

Conclusion: Although anticoagulation guidelines now emphasize patient self-management (PSM) only, optimal PST remains an integral process in PSM delivery. In the patients studied, the results of this analysis suggest that PST at the IHS facility provided a convenient, alternative method for management of chronic warfarin therapy for qualified patients. More than half of the patients demonstrated improvement in TTR. Although there is a learning curve immediately following PST initiation, the mean TTR for the entire PST period increased modestly when compared to the time period prior to PST.

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1. Petersen P, Boysen G, Godtfredsen J, Andersen E, Andersen B. Placebo-controlled, randomized trial of warfarin and aspirin for prevention of thromboembolic complications in chronic atrial fibrillation: the Copenhagen AFASAK study. Lancet. 1989;1(8631):175-9.

2. Boston Area Anticoagulation Trial for Atrial Fibrillation Investigators. The effect of low-dose warfarin on the risk of stroke in patients with nonrheumatic atrial fibrillation. N Engl J Med. 1990;323(22):1505-11.

3. Ezekowitz M, Bridgers S, James K, Carliner N, Colling C, Gornick C, Krause-Steinrauf H, Kurtzke J, Nazarian S, Radford M, Rickles F, Shabetai R, Deykin D. Warfarin in the prevention of stroke associated with nonrheumatic atrial fibrillation: Veterans Affairs Stroke Prevention in Nonrheumatic Atrial Fibrillation Investigators. N Engl J Med. 1992;327(20):1406-12.

4. Stroke Prevention in Atrial Fibrillation Investigators. Stroke Prevention in Atrial Fibrillation Study: final results. Circulation. 1991;84(2):527-39.

5. European Atrial Fibrillation Trial Study Group. Secondary prevention in non-rheumatic atrial fibrillation after transient ischemic attack or minor stroke. Lancet. 1993;342(8882):1255-62.

6. Szekely P. Systemic embolization and anticoagulant prophylaxis in rheumatic heart disease. Br Med J. 1964;1(5392):1209-12.

7. Fleming HA. Anticoagulants in rheumatic heart-disease. Lancet. 1971;2(7722):486.

8. Adams GF, Merrett JD, Hutchinson WM, Pollock AM. Cerebral embolism and mitral stenosis: survival with and without anticoagulants. J Neurol Neurosurg Psychiatry. 1974;37(4):378-83.

9. Silaruks S, Thinkhamrop B, Tantikosum W, Wongvipaporn C, Tatsanavivat P, Klungboonkrong V. A prognostic model for predicting the disappearance of left atrial thrombi among candidates for percutaneous transvenous mitral commissurotomy. J Am Coll Cardiol. 2002;39(5):886-91.

10. Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and management of the vitamin k antagonists. Chest. 2008;133(6 Suppl):160S-198S. doi: 10.1378/chest.08-0670.

11. Palareti G, Legnani C, Guazzaloca G, Lelia V, Cosmi B, Lunghi B, Marchetti G, Poli D, Pengo V. Risk factors for highly unstable response to oral anticoagulation: a case control study. Br J Haematol. 2005;129(1):72-8.

12. Forfar JC. Prediction of hemorrhage during long-term oral coumarin anticoagulation by excessive prothrombin ratio. Am Heart J. 1982;103(3):445-6.

13. White HD, Gruber M, Feyzi J, Kaatz S, Tse HF, Husted S, Albers GW. Comparison of outcomes among patients randomized to warfarin therapy according to anticoagulant control: results from SPORTIF III and V. Arch Intern Med. 2007;167(3):239-45.

14. National Diabetes Fact Sheet, 2011. Accessed on December 4, 2012. Available at

15. Heneghan C, Alonso-Coella P, Garcia-Alamino JM, Perera R, Meats E, Glasziou P. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. Lancet. 2006;367(9508):404-11.

16. White RH, McCurdy SA, von Marensdorff H, Woodruff DE Jr, Leftgoff L. Home prothrombin time monitoring after the initiation of warfarin therapy. Ann Intern Med. 1989;111(9):730-7.

17. Khan TI, Kamali F, Kesteven P, Avery P, Wynne H. The value of education and self-monitoring in the management of warfarin therapy in older patients with unstable control of anticoagulation. Br J Haematol. 2004;126(4):557-64.

18. Matchar DB, Jacobson A, Dolor R, Edson R, Uyeda L, Phibbs CS, Vertrees JE, Shih MC, Holodniy M, Lavori P; THINRS Executive Committee and Site Investigators. Effect of Home Testing of International Normalized Ratio on Clinical Events. N Engl J Med. 2010 Oct 21;363(17):1608-20. doi: 10.1056/NEJMoa1002617.

19. Centers for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management (CAG-00087N) [Memorandum]. Decision memo for prothrombin time (INR) monitor for home anticoagulation management. September 18, 2001.

20. Horstkotte D, Piper C, Wiemer M. Optimal frequency of patient monitoring and intensity of oral anticoagulation therapy in valvular heart disease. J Thromb Thrombolysis. 1998;5(Suppl 1-3):19-24.

21. Centers for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management (CAG-00087R) [Memorandum]. Decision memo for prothrombin time (INR) monitor for home anticoagulation management (CAG-00087R). March 19, 2008.

22. Holbrook A, Schulman S, Witt DM, Vandvik PO, Fish J, Kovacs MJ, Svensson PJ, Veenstra DL, Crowther M, Guyatt GH; American College of Chest Physicians. Evidence-based management of anticoagulant therapy. Chest. 2012 Feb;141(2 Suppl):e152S-84S. doi: 10.1378/chest.11-2295.

23. Ansell J, Jacobson A, Levy J, Voller H, Hasenkam JM. Guidelines for implementation of patient self-testing and patient self-management of oral anticoagulation. Int J Cardiol. 2005;99(1):37-45.

24. Rosendaal FR, Cannegieter SC, van der Meer FJM, Briet E. A method to determine the optimal intensity of oral anticoagulant therapy. Thromb Haemost. 1993;69(3):236-9.

25. CoaguChek XS System [package insert]. Indianapolis, IN: Roche Diagnostics Corporation; 2006.

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