International Journal of Hematology

, Volume 100, Issue 2, pp 119–124 | Cite as

Telephone versus office-based management of warfarin: impact on international normalized ratios and outcomes

  • Laura G. Stoudenmire
  • Christina E. DeRemer
  • Hazem ElewaEmail author
Original Article


Studies have concluded that telephone-based management of warfarin is an effective alternative to in-office management. High rates of patient and physician satisfaction have been reported with telephone-based monitoring. Proposed benefits of telephone-based monitoring include time- and cost savings for patients and healthcare providers alike as well as increased access to care for those patients who have difficulty making in-office appointments. This study aimed to evaluate the impact of telephone versus office-based management of warfarin on extreme INR values. A retrospective cohort study was conducted to assess outcomes of patients receiving warfarin managed either by telephone or in-office appointments. The primary endpoint of the study was the frequency of extreme INR values, defined as an INR ≤1.5 or ≥4.5. A total of 110 patients were evaluated; subjects were distributed 2:1 between the in-office and telephone groups. Baseline characteristics were similar between groups. Subjects followed via telephone had a twofold increase in the incidence of extreme INR values compared to the patients followed in-office (15.18 vs. 7.98 %; p < 0.0001). Overall TTR was similar between groups (85.39 vs. 80.38 %, p = 0.1171). There was no difference between the two groups in the incidence of major bleeding events (2.67 vs. 0 %, p = 1.00), thromboembolic events (8 vs. 0 %, p = 0.1740), or hospitalizations related to anticoagulation therapy (6.67 vs. 0 %, p = 0.1758). Patients monitored via telephone had a higher incidence of extreme INR values than patients followed in-office, which may lead to an increased incidence of adverse outcomes in the long-term. Well-designed, prospective studies are needed to confirm such findings.


Anticoagulation clinic Monitoring Warfarin Telephone Pharmacist managed 


Conflict of interest

The authors have no conflict of interest to report.


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Copyright information

© The Japanese Society of Hematology 2014

Authors and Affiliations

  • Laura G. Stoudenmire
    • 1
  • Christina E. DeRemer
    • 2
  • Hazem Elewa
    • 3
    Email author
  1. 1.Department of PharmacySaint Thomas Rutherford HospitalMurfreesboroUSA
  2. 2.Department of PharmacyGeorgia Regents Health SystemAugustaUSA
  3. 3.Clinical Pharmacy and Practice Section, College of PharmacyQatar UniversityDohaQatar

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