Design of an Online Continuing Education Module: Herbal and Dietary Supplements Impact Warfarin Safety and Efficacy

Design of an Online Continuing Education Module: Herbal and Dietary Supplements Impact Warfarin Safety and Efficacy

Jennifer L. Strohecker (Intermountain Medical Center, USA) and Wendy Athens (University of Florida, USA)
DOI: 10.4018/978-1-4666-1936-4.ch015


The core instructional objective was a behavior change: Clinicians must ask patients about HDS use when taking a medical history and document this use in the medical record. HDS use is prevalent among Americans and sales are increasing. When taken in conjunction with prescription medications, HDS-drug interactions are common and may result in unexpected and serious patient harm. Patient’s failure to report HDS use to their medical provider, and a provider’s failure to ask specifically about HDS use, further complicate the picture.
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Setting The Stage

Patient safety was the impetus for clinician training within a large western U.S. healthcare organization. It was deemed crucial for a clinician to recognize that HDS use is common and underreported, and that this use may influence the efficacy and safety of drugs with a narrow safety window, such as warfarin. Warfarin (Coumadin®) is a gold standard anticoagulant for prevention of stroke and venous thromboembolism, yet many factors can influence warfarin safety and efficacy. Variations in diet, alcohol consumption, and drug or herbal supplement use may alter warfarin levels, leading to either bleeding complications or treatment failure (stroke). Warfarin accounts for more emergency room visits than any other drug (Budnitz, 2007), and in 2009, the Joint Commission made the appropriate use of warfarin a National Patient Safety Goal (

National surveys indicate that 50% of U.S. adults (>50 years) use Herbal and Dietary Supplements (HDS), and use may be greater in warfarin-treated patients (Strohecker, 2012). Of great concern is the lack of communication between patient and clinician about HDS use. Nearly two-thirds of Americans who use HDS, including warfarin-treated patients, fail to report use to their medical provider (Barnes, Bloom, & Nahin, 2008; Strohecker, 2012). This translates to the odds of 5.4 to 1, or 81% chance, that the patient is taking HDS and the clinician never asks about their use (Strohecker, 2012). This communication gap leaves room for dangerous drug-herb interactions, as the majority of most commonly used HDS have the potential to interact with warfarin (Strohecker, 2012).

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