Lina Palaiodimou, MD
Lip GYH, Keshishian A, Li X, Hamilton M, Masseria C, Gupta K, et al. Effectiveness and Safety of Oral Anticoagulants Among Nonvalvular Atrial Fibrillation Patients: The ARISTOPHANES Study. Stroke. 2018
The ARISTOPHANES study is a large retrospective observational study with real-world data pooled from 5 data sources in the United States, in order to compare stroke/systemic embolism (SE) and major bleeding (MB) among nonvalvular atrial fibrillation patients treated with either non-vitamin K antagonist oral anticoagulants (NOACs) or warfarin.
The researchers of this study collected data about a total of 321182 patients with a diagnosis of AF, who had an active medical and pharmacy health plan enrollment and were prescribed treatment with either NOAC or warfarin according to pharmacy claims. Exclusion criteria were the following: evidence of valvular heart disease, venous thromboembolism, previous oral anticoagulant treatment, transient AF due to treatable causes (pericarditis, hyperthyroidism, thyrotoxicity), heart valve replacement or transplant, pregnancy and recent surgical operations. Demographic data, Charlson Comorbidity Index score, baseline bleeding and stroke/SE history, comorbidities, baseline comedication and dose of NOAC were recorded about all patients. In contrast, reason for lose-dose NOAC prescription, creatinine clearance, international normalized ratio (INR) measurements in warfarin-treatment group and patient adherence data were not available. The outcome measures were time to stroke (either ischemic or hemorrhagic) or systemic embolism and time to major bleeding, either gastrointestinal or intracranial or at other key sites (eyes, pericardium, urinary tract, joints). Identification of these events were based just on hospitalization incidence with stroke/SE or MB as the principal diagnosis according to International Classification of Diseases, Ninth Revision (ICD-9). Mortality due to all-causes was also evaluated, but just for the patients enlisted in only one out of five data sources. Patients were followed up each for a different period, according to drug discontinuation date, switch to another drug date, death, end of medical and pharmacy health plan enrollment, or end of study period, whichever occurred first. In the conducted sensitivity analysis, the follow-up period was restricted to 1 year, to better achieve balance between the cohorts.