Warfarin Education and Monitoring in Medicare Patients with Atrial Fibrillation: Results from the National Stroke Project
Background: Anticoagulation with warfarin is recommended for stroke prevention for many patients with atrial fibrillation (AF). It is important that patients understand the appropriate use of warfarin and are monitored for optimal drug dosing. As part of HCFA’s initiative, we studied data related to these aspects of warfarin use. Methods: Project findings were based on abstracted data from a national sample of Medicare inpatient medical records with a principal or secondary diagnosis of AF (ICD-9-CM code 427.31) and discharged 4/98–3/99. All U.S. states, the District of Columbia and Puerto Rico were sampled using a systematic random approach. Patients included in analysis had documentation of a prescription for warfarin at discharge. Results: Of the 38,925 cases reviewed, 14,237 met the inclusion criteria. Nationwide, 2,274 (unadjusted rate, 16.0%) patient/family/caregivers received warfarin education. The rates varied from 5.7% to 26.9%. Univariate analyses showed that education was provided less frequently to adults 85 years and over (p<0.001, rate=11.1%, OR=0.60, 95% CI=0.53–0.69). Education was provided more frequently to Asians (p<0.001, n=77, rate=32.5%, OR=2.55, 95% CI=1.58–4.11) and Native Hawaiian/Pacific Islanders (p<0.03, n=24, rate=33.3%, OR=2.64, 95% CI=1.13–6.17). Of the 14,237 patients that were prescribed warfarin at discharge, 7,959 (unadjusted rate, 55.9%) had a documented plan for a prothrombin time (PT)/International Normalized Ratio (INR). The rates varied from 21.3% to 67.6%. Univariate analyses showed that a planned PT/INR was documented less frequently for adults 85 years and over (p<0.001, rate=52.6%, OR=0.85, 95% CI=0.78–0.93), African-Americans (p<0.005, rate=50.2%, OR=0.79, 95% CI=0.67–0.93) and Asians (p<0.02, rate=41.6%, OR=0.56, 95% CI=0.36–0.88). Conclusions: Our results suggest that many patients receiving anticoagulation for stroke prevention are not receiving drug education and follow-up monitoring. Important high-risk subgroups were less likely to receive these aspects of anticoagulation management.