Quality of Oral Anticoagulation Management in Pharmacist Vs Nurse Managed Models of Care

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Systematic models of anticoagulation management result in better clinical outcomes than routine medical care. At the University of Illinois at Chicago Medical Center (UIMCC) systematic anticoagulation management is provided via 2 models of care: a pharmacist managed antithrombosis clinic (PMATC) and a nurse managed anticoagulation clinic (NMAC). The objective of this study was to evaluate the quality of oral anticoagulation management in these two models of care by assessing efficacy, safety, monitoring and resource utilization outcomes. A retrospective, observational cohort study was conducted between January 2005 and April 2007. A total of 200 patients, 100 in each group, were randomly selected and contributed 179.3 and 206.8 patient-years of therapy for the PMATC and NMAC respectively (p<0.0001). Venous thromboembolism and atrial fibrillation were the 2 most common indications for anticoagulation therapy, although the PMATC group managed a higher proportion of patients with shorter-term venous indications then the NMAC group (78% vs 4% respectively; p<0.0001). The PMATC group reached goal INR faster after initiating therapy then the NMAC group. (median of 9 days vs 22 days respectively; p=0.0003). The mean % of patients with INR controlled within the therapeutic range (TTR) was 65.8% in the PMATC group and 71.2% in the NMAC group (p=0.009). The PMATC group had a higher proportion of difficult to manage patients who were non-compliant with their clinic monitoring appointments and non-compliant with their warfarin therapy as compared to the NMAC group. (median number of missed appointments per year was 4.8 vs 1.0 respectively; p < 0.0001 and median number of deviations from prescribed warfarin dose was 16.6 vs 3.5 respectively; p < 0.0001). The percent of patients who developed thromboembolic events and major bleeding complications during therapy were similar in the PMATC and NMAC groups (1.2% vs 0.5% per patient-year of therapy, respectively; RR 2.40; 95% CI 0.096 to 4.26; and 4.7% vs. 4.9% per patient-year of therapy, respectively; RR 0.96; 95% CI, 0.28 to 3.30). Hospital admissions and emergency department visits due to non-therapeutic INRs were higher in the NMAC group compared to the PMATC group (9.2% vs 0.6% per patient-year of therapy, respectively; RR 0.06; 95% CI 0.004 to 0.79; and 1.5% vs 0 per patient-year of therapy, respectively.) Patients who spent > 60% of the time in therapeutic INR range had a lower median number of missed clinic monitoring appointments and a lower median number of deviations from the prescribed warfarin dose as compared to patients who spent < 60% of the time in the therapeutic INR range (1.8 vs 4.0, respectively; p=0.0002 and 9.1 vs. 12.8, respectively; p=0.02). In this study, the PMATC model showed better outcomes in attaining a faster therapeutic INR after initiating warfarin therapy and also demonstrated more judicious resource utilization by lower hospitalization rates and emergency room visits due to non-therapeutic INRs. Although the TTR was lower in the PMATC group, the 2 groups faired similarly with regards to clinical outcomes such as recurrent thromboembolism and major bleeding complications. The difference in TTR can be attributed to the higher proportion of more difficult to manage, non-compliant patients in the PMATC group. Both models of care were found to be well within acceptable limits of national benchmark quality data for systematic anticoagulation management, although the PMATC model had better resource utilization outcomes.