Elsevier

American Heart Journal

Volume 179, September 2016, Pages 186-191
American Heart Journal

Clinical Investigation
Trends in antithrombotic therapy for atrial fibrillation: Data from the Veterans Health Administration Health System

https://doi.org/10.1016/j.ahj.2016.03.029Get rights and content

Background

Although controversial, several prior studies have suggested that oral anticoagulants (OACs) are underused in the US atrial fibrillation (AF) population. Appropriate use of OACs is essential because they significantly reduce the risk of stroke in those with AF. In the >2 million Americans with AF, OACs are recommended when the risk of stroke is moderate or high but not when the risk of stroke is low. To quantify trends and guideline adherence, we evaluated OAC use (either warfarin or dabigatran) in a 10-year period in patients with new AF in the Veterans Health Administration.

Methods

New AF was defined as at least 2 clinical encounters documenting AF within 120 days of each other and no previous AF diagnosis (N = 297,611). Congestive Heart Failure, Hypertension, Age > 75, Diabetes, and Stroke (CHADS2) scores were determined using age and diagnoses of hypertension, diabetes, heart failure, and stroke or transient ischemic attack during the 12 months before AF diagnosis. Receipt of an OAC within 90 days of a new diagnosis of AF was evaluated using VA pharmacy data.

Results

Overall, initiation of an OAC fell from 51.3% in 2002 to 43.1% in 2011. For patients with CHADS2 score of 0, 1, 2, 3, 4, and 5-6, the proportions of patients prescribed an OAC showed a relative decrease of 26%, 23%, 14%, 12%, 9%, and 13%, respectively (P < .001). Clopidogrel use was stable at 10% of the AF population.

Conclusions

Among US veterans with new AF and additional risk factors for stroke, only about half receive OAC, and the proportion is declining.

Section snippets

Patients

Patients with a new episode of AF from October 1, 2001, through September 30, 2011, were identified in VA Outpatient Care Files and Inpatient Treatment Files using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code 427.31. There were 406,168 new AF episodes, defined as at least 2 encounters for AF within 120 days of each other and no AF-related encounters during the 12 months prior. To ensure complete diagnostic information during the prior

Results

The number of patients with new AF diagnoses increased, with new diagnoses increasing from 51,133 during the first year of observation (2002-2003) to 68,774 during the final year of observation (2010-2011). The median (interquartile range) CHADS2 remained unchanged at 2 (1-3). During the study period, the proportion of patients age ≥81 years increased from 23% to 30%, and those with renal disease increased from 7.9% to 14.1% (Table I).

In aggregate, 47% of patients received an OAC within 90 days

Discussion

This study showed a general decline in the rates of initiating OAC therapy from 2002 to 2011 among veterans with new AF. Patients with low stroke risk had significant decreases in OAC use, as hypothesized, but more than one-third of patients with a CHADS2 score of 0 still received an OAC in the final years of the study. Surprisingly, patients with higher risks for stroke also had significant declines in use of OAC therapy. This decline is concerning because patients with AF who fail to receive

Acknowledgements

This work was supported by a Mentored Career Enhancement Award in Patient Centered Outcomes Research for Mid-Career and Senior Investigators (K18) provided to Dr. Vaughan Sarrazin by the Agency for Healthcare Research and Quality, and by the Health Services Research and Development Service of the Department of Veterans Affairs. Dr Peter Cram is supported by a K24 award from National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) (AR062133). The authors do not have any

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