Authors: Wang L, Fritschel E, Baser O.

Background: Atrial fibrillation (AF) is a common clinical problem and potent risk factor for stroke. However, real-world effectiveness and outcomes for AF patients are not well described.

Objective: To compare the economic and clinical impact of stroke and warfarin use on patients with non-valvular atrial fibrillation (NVAF).

Methods: This was a retrospective analysis of medical and pharmacy claims of NVAF patients from a large commercial health insurance database (01/01/2005-12/31/2007). Patients were grouped according to stroke or warfarin prescription status. For all groups, demographic, clinical, and pharmaceutical characteristics were analyzed descriptively. Risk-adjusted overall and cardiovascular-related hospital readmission rates in 30 days, length of stay (LOS), clinical outcomes, and health care costs were assessed using propensity score matching. Costs were adjusted to 2007 U.S. dollars using the medical component of the U.S. Consumer Price Index.

Results: Out of 18,575 NVAF patients, 3.1% (n=575) experienced a stroke event. Stroke patients were older on average (78.94 vs 77.28 years, p-value<0.0001) with significantly higher risk-adjusted inpatient mortality (7.14% vs 2.09%, p-value<0.0001), emergency room visits (79.97% vs 46.34%, p-value<0.0001), and average LOS measures (overall: 10.20 vs 6.83 days, p<0.0001; cardiovascular-related: 8.35 vs 5.90 days, p-value<0.0001). Despite the similarity in Charlson Comorbidity Index scores compared to non-stroke controls, stroke patients significantly higher clinical outcome rates during follow-up for acute coronary syndrome (ACS), ischemic attack, major and minor bleeding patients (p-values<0.0100), and the total cost incurred was nearly three times greater ($33,506 vs $13,921, p-values<0.0001). NVAF patients were commonly prescribed warfarin (65.60%) and appeared to have a lower prevalence of clinical outcomes, while not incurring significantly higher follow-up costs compared to those not prescribed warfarin ($12,739, standard deviation [SD]=$19,842 vs $15,358; SD=$45,446; p-value>0.0500). However, a significantly greater proportion of patients with major and minor bleeding were prescribed a combination of warfarin and antiplatelets than those without these events.

Conclusions: A stroke after an NVAF diagnosis has a major clinical impact, which translates into a significant economic burden for patients. Warfarin prescriptions did not significantly impact total health care costs, though caution is advised to minimize hemorrhagic events.

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