Health Services Research & Development

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2006 HSR&D National Meeting Abstract


3035 — Quality of Oral Anticoagulant Treatment among Atrial Fibrillation Patients Post-Stroke

Author List:
Kwon SJ (University of Florida/RORC)
Beyth RJ (University of Florida/RORC)
Matchar DB (Duke University)

Objectives:
To examine the quality of anticoagulation in patients with acute ischemic stroke and atrial fibrillation (AF) based on evaluation of International Normalized Ratio (INR).

Methods:
Using the fiscal year 2003 (FY03) Patient Treatment File (PTF) main, we identified patients with acute ischemic stroke (433.x1, 434.x1, 435, 436). Of these individuals, we examined PTF main, extended, and outpatient files retrospectively for 3 years prior to their stroke to identify the presence of AF (427.31). After excluding transient AF and acute death post-stroke, we used the Pharmacy Benefit Management database to determine those patients prescribed warfarin during the first 28 days after admission. For the exposed, we linked to the Decision Support System National Data Extract LAb test Results (LAR) to examine: (1) proportion of patients who had INR testing done during the year following the stroke admission, (2) the time interval between INR tests, and (3) the time-in-therapeutic range using Rosendaal’s interpolation methods.

Results:
Among those who were exposed to warfarin in the first 28 days post-stroke, 70.8% of patients had at least one INR test recorded in LAR within 1 year from their admission date (mean INRs/person/yr: 12.09 + 7.91). 32% of INR intervals were less than 7 days, 48% were between 8-30 days, while 20% were more than 30 days. INRS were within therapeutic range (2.0-3.0) 49.9%, sub-therapeutic (<2.0) 30.3%, and supra-therapeutic (>3.0) 19.7%.

Implications:
Optimal management of warfarin therapy requires a coordinated approach including the tracking of INR test results. Among stroke patients with AF who received warfarin from VA, 1/3 did not have an INR recorded in LAR within the 1-year period post-stroke, and the time between INR testing exceeded more than 30 days in 1/5 of patients. Patients were in therapeutic range for one-half the time.

Impacts:
Efforts to optimize the management of anticoagulant therapy need to consider the practical aspects of tracking, recording, and monitoring the INR to minimize patients’ time outside of therapeutic range. Such systems approach have the potential to improve outcomes and quality of life by decreasing bleeding and thromboembolic events with better tracking and monitoring systems.