Warfarin use increased from 24.5% to 56.3% between 1992 and 2002, which was associated with a decline in overall ischemic stroke rates from 46.7 to 19.5 per 1000 patient-years.
Cohort
Does warfarin use reduce the risk of stroke in Medicare patients aged ≥ 65 years with atrial fibrillation?
Increased warfarin use among Medicare patients with atrial fibrillation from 1992 to 2002 was associated with a significant decline in ischemic stroke rates, validating clinical trial evidence in real-world practice.
BACKGROUND AND PURPOSE: Clinical trials have illustrated warfarin's protective effect on stroke risk in patients with atrial fibrillation (AF). The current study investigated temporal trends in AF prevalence, warfarin use, and its relation to stroke risk in Medicare patients with AF from 1992 to 2002. METHODS: The Medicare 5% sample for 1992 to 2002 was used to create 1-year cohorts of patients with Medicare as primary payer throughout the year. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify AF, ischemic and hemorrhagic stroke, and comorbid conditions. A previously validated surrogate measure, prothrombin/international normalized ratio claims, was used to identify warfarin use. Cox proportional hazards regression was used to examine time to stroke with warfarin use as a time-dependent variable. RESULTS: Among Medicare patients aged > or = 65 years, AF prevalence increased from 3.2% in 1992 to 6.0% in 2002 with higher prevalence in older subsets of the study population. Among patients with AF, warfarin use increased significantly (P< or = 0.001) for each year examined, from 24.5% in 1992 to 56.3% in 2002. Stroke rates per 1000 patient-years declined from 46.7 in 1992 to 19.5 in 2002 for ischemic stroke but remained fairly steady for hemorrhagic stroke (range, 1.6 to 2.9). Time-to-event modeling confirmed a protective association of warfarin against ischemic stroke among Medicare patients with AF. CONCLUSIONS: This analysis represents an observational validation of stroke prevention in AF trials. The significant increase in warfarin use among patients with AF illustrates diffusion of trial evidence into clinical practice.
Lakshminarayan et al. (Fri,) conducted a cohort in Atrial fibrillation. Warfarin vs. No warfarin was evaluated on Ischemic stroke. Warfarin use increased from 24.5% to 56.3% between 1992 and 2002, which was associated with a decline in overall ischemic stroke rates from 46.7 to 19.5 per 1000 patient-years.