Sustained Impact of Anticoagulant Control Achieved in an Anticoagulation Management Service After Transfer of Management to the Primary Care Physician

Study Objectives

To determine whether the impact of anticoagulant control achieved in an Anticoagulation Management Service (AMS) is sustained after transfer of anticoagulation management to the primary care physician (PCP), and to assess patient satisfaction with their anticoagulation management by both the AMS and PCP.

Design

Prospective, randomized trial.

Setting

Pharmacist-directed ambulatory AMS located in a tertiary medical care facility and PCP practices in Canada.

Patients

Sixty-two adults who had received at least 6 months of warfarin therapy managed by the AMS.

Intervention

Patients were randomly assigned to remain with AMS care (32 patients) or to transfer their anticoagulation management care to their PCP (30 patients). After 4.5 months of care, patients in both groups completed a validated survey instrument assessing their satisfaction with the management of their warfarin therapy.

Measurements and Main Results

Of 295 patients screened, most were excluded from the study for denying consent or for having previous bleeding or clotting complications while taking warfarin. Patients in the AMS and PCP groups who completed the study were similar in age (median 70 and 76 yrs, respectively), and most had atrial fibrillation as an indication for warfarin (75% and 83%, respectively). The primary outcome measure—mean percentage of time within the desired international normalized ratio (INR) range after 6 months—was compared between the two groups, using both the actual range (INR 2.5 ± 0.5) and an expanded range (INR 2.5 ± 0.7). No significant difference was noted in this outcome between the groups (73.5 ± 19.1% vs 76.9 ± 24.5% for the AMS vs PCP groups, p=0.54). Other outcome measures were rates of thrombotic and hemorrhagic events resulting in emergency department visits or hospitalizations, patients’ overall satisfaction with warfarin therapy, and patients’ preferred anticoagulation management strategy. Two hemorrhagic events and one thrombotic event occurred in each group. Patients were more satisfied with their anticoagulant management by the AMS relative to PCP care (p=0.01), and given the choice, patients preferred AMS care (p=0.001).

Conclusion

During this 6-month trial, anticoagulation control did not significantly differ between patients who continued to receive anticoagulation management by the AMS and those who transferred to their PCP for anticoagulation management, indicating that the effects of AMS care were sustained. Although patients were more satisfied and preferred to stay with AMS care, this study shows that select patients could have their anticoagulation care transferred to their PCP without compromising anticoagulation control.