Anticoagulation Management Outcomes in Veterans: Office vs Telephone Visits
Results
A total of 111 patients met inclusion criteria (Table 1). Most patients were elderly males with AF or atrial flutter as their primary indication for warfarin therapy. No statistically significant difference was found for percentage INRs in strict range (56.8% in office vs 56.9% in telephone, P = .98) or TTR (65.9% in office vs 62.72% in telephone, P = .23) for patients who transitioned from office to telephone visits (Table 2). Similar results were found within the nonstrict range. 
In examining safety, 5 major AEs occurred. One patient had 2 thrombotic pulmonary embolism events. This patient had a history of nonadherence with warfarin therapy. Three major bleeding events occurred (2 in the telephone group and 1 in the office group). Two bleeding events led to ED visits, and 1 event led to hospitalization. Although 43% of patients had a procedure during the study period, only a portion of patients received bridging with low-molecular-weight heparin (LMWH). None of the 3 reported bleeding events discovered during the study were associated with recent LMWH use. No events were fatal (Table 3).
Discussion
This study demonstrates that patients transitioned from office to telephone visits for warfarin management will have no significant change in their TTR. Additionally, patients had similar rates of major AEs before and after transition, although there were few events overall.
Previous research comparing anticoagulation outcomes in telephone vs office visits also has described outcomes to be similar between these 2 management models. Wittkowsky and colleagues examined 2 university-affiliated clinics to evaluate warfarin outcomes and AEs in patients in each management model (office vs telephone) and found no difference in outcomes between the 2 management models.9
Staresinic and colleagues designed a prospective study of 192 patients to evaluate TTR and AEs of the 2 management models at the William S. Middleton Memorial Veterans Hospital in Madison, Wisconsin.10 This study found no difference between the 2 groups in percentage of time maintained within INR range or AEs and concluded that the telephone model was effective for anticoagulant management.
A retrospective study by Stoudenmire and colleagues evaluated office vs telephone management effects on extreme INR values (≤ 1.5 or ≥ 4.5), TTR, and AEs.11 This study found overall TTR and AEs to be similar between groups, but the telephone clinic had a 2-fold increase in extreme INR values compared with the office clinic.11
The current study differs from the previously discussed studies in that it evaluated outcomes for the same patients before and after the transition to telephone. This study did not exclude specific patients from telephone clinic. In the Wittkowsky study, patients were enrolled in the telephone clinic based on criteria such as patient disability or living long distances from the clinic.9 Additionally, in the current study, patients transitioned to telephone visits did not have scheduled office visits for anticoagulation management. In contrast, patients in the Staresinic study had routine anticoagulation office visits every 3 months, thus it was not a true telephone-only clinic.10
This study’s findings support prior studies’ findings that telephone clinics are acceptable for anticoagulation management. Furthermore, safety does not seem to be affected when transitioning patients, although there were few AEs to review. Providers can use telephone clinics to potentially decrease cost and facilitate access to care for patients.
Limitations
Patients were required to be in office and telephone for a sequential 6 months, and this may have produced selection biases toward patients who adhered to appointments and who were on long-term warfarin therapy. Many patients that were excluded from the study transitioned back and forth between the 2 management models. Due to the retrospective nature of this study, the authors were unable to control for all confounding variables. Patients also were not randomly assigned to be transitioned from office to telephone. Although a strength of this study was the limited telephone clinic selection criteria, there may be a few individual situations in which the pharmacist’s clinical judgment influenced the transition to the telephone clinic, creating selection bias.
There may be time bias present as clinical guidelines, providers, and clinic population size differed over the study period and might have influenced management. The population of VA patients was mainly elderly males; therefore, the study results may not be applicable to other populations. Last, the results of the study are reflective of the VANTHCS clinic structure and may not be applicable to other clinic designs.
Conclusion
Veterans in a pharmacist-managed anticoagulation clinic experienced the same outcomes in terms of TTR and major AEs when transitioned from the traditional face-to-face office visits to telephone visits. The study supports the safety and efficacy of transitioning patients from a pharmacist-managed anticoagulation office clinic to telephone clinic.
