Comparison of patient outcomes among Alaska native people using a warfarin dosing algorithm versus patient management system software

Patient management system software can facilitate improved outcomes for orally anticoagulated patients. The pharmacist-staffed anticoagulation management service (AMS) at the Alaska Native Medical Center transitioned from a warfarin dosing algorithm to a software-based patient management system that included dose adjustment recommendations. A quality assurance assessment approved by the institution’s medical director of research was conducted to determine the effect on patient outcomes. A retrospective comparison of AMS patient outcomes was conducted for the time period of 113 days before (PRE) and after (POST) the May 11, 2006 implementation of Dawn AC software, an anticoagulation patient management system. All orally anticoagulated patients, regardless of indication, seen in the AMS from January 18 to August 31, 2006, were evaluated. The software was populated with all PRE and POST patient data including International Normalized Ratio (INR) values from January 18 through August 31. Time within therapeutic range was calculated within the software by the Rosendaal method and was analyzed using a 2-sample binomial test of equal proportions. The mean interval between INR measurements was measured. Patient outcomes included any hemorrhagic or thrombotic event that led to a hospitalization or a visit to the emergency department (ED) or outpatient clinic (OPD) and were analyzed using an exact 2-sample Poisson test. Outcomes and INR values were analyzed for patients in the PRE group (N = 94) with a total of 7,828 days of treatment (83.3 average treatment days per patient; 21.4 patienttreatment-years) while the POST group (N = 110) had a total of 8,956 days of treatment (81.4 average treatment days per patient; 24.5 patient-treatment-years). The overall time within therapeutic range decreased from 64.0% in the PRE group to 61.6% in the POST group (P \ 0.01). The mean interval between INR measurements in the PRE group was nearly equal to the POST group (15.8 vs. 15.9 days). No thrombotic events occurred in the PRE or POST groups. The occurrence of hemorrhagic events decreased from 16 in the PRE group; 0.75 events per patient-treatment-year; to 11 in the POST group; 0.45 (P = 0.25). The occurrence of all hemorrhagic visits (initial event and any follow up) to ED and OPD decreased from 20 visits in the PRE group; 0.93 visits per patient-treatment-year to 14 visits in the POST group; 0.57; however this difference was not statistically significant (P = 0.17). The incidence of hemorrhagic ED visits was identical between the PRE and POST groups (8 visits; 0.37 visits per patient-treatment-year vs. 9 visits; 0.37); (P = 1). The incidence of hemorrhagic OPD visits was higher in the PRE group versus the POST group (12 visits; 0.56 visits per patient-treatmentyear vs. 5 visits; 0.20); (P = 0.05). One admission occurred in both the PRE and POST groups (0.05 admissions per patient-treatment-year vs. 0.04); (P-value not calculated due to sample size limitations). The number of admission days was lower for the PRE group, (4 days; 0.19 days per patient-treatment-year) than the POST group (6 days; 0.24); (P-value not calculated due to sample size limitations). Despite a significant decrease in time within therapeutic range, a decrease in hemorrhagic events and a significant decrease in hemorrhagic outpatient clinic visits occurred among Alaska Native people after implementation of oral anticoagulation patient management software.