Antithrombotic Prescription at Discharge in Medicare Patients with Ischemic Stroke/Transient Ischemic Attack: Results from the National Stroke Project
Background: Antiplatelet agents have been shown to be effective for secondary stroke prevention in patients with ischemic stroke (IS) or transient ischemic attack (TIA). As part of HCFA’s National Stroke Project, we examined patterns of use of antithrombotic agents for inpatients with IS or TIA. Methods: Findings were based on abstracted data from a sample of Medicare inpatient medical records (discharge dates 4/98 - 3/99). All U.S. states, the District of Columbia and Puerto Rico were sampled using a systematic random approach. Each record had a principal diagnosis of one of the following ICD-9-CM codes: 362.34, 433.xx, 434.xx, 435.0, 435.1, 435.3, 435.8, 435.9 or 436. The main outcome measure was the frequency of eligible patients with a prescription or a plan for antithrombotic therapy at discharge. Antithrombotics were aspirin, clopidogrel, dipyridamole, ticlopidine and warfarin. Results: Of the 36,650 cases reviewed, 25,659 met the criteria for inclusion in the indicator. A large percentage of excluded cases (53.1%) were removed due to a history or current finding of hemorrhage. Nationwide, 20,947 (unadjusted rate 81.6%) patients were prescribed an antithrombotic at discharge or had a plan for starting an antithrombotic after discharge. The state-specific rates ranged from 72.0% to 90.1%. Univariate analyses showed this therapy was prescribed less frequently (p<0.001) for adults 85 years and over (rate=77.8%, OR=0.74, 95% CI=0.69–0.80), women (rate=80.4%, OR=0.83, 95% CI=0.78–0.89) and African-Americans (rate=77.6%, OR=0.76, 95% CI=0.68–0.85). Asians were found to have been prescribed this therapy more frequently than other races (p<0.02, rate=87.2%, OR=1.54 95% CI=1.10–2.16). Among those IS/TIA patients who also had atrial fibrillation (AF), 57.1% received warfarin. Conclusions: Antithrombotic agents are not prescribed for almost one-fifth of eligible Medicare inpatients with IS/TIA. For those with IS/TIA and AF, a large proportion are not treated with warfarin. These results show important opportunities for improvement in secondary stroke prevention for Medicare patients.