Development of a Conceptual Model of Adherence to Oral Anticoagulants to Reduce Risk of Stroke in Patients with Atrial Fibrillation

BACKGROUND: Oral anticoagulant (OA) medication is the recommended therapy for reducing the risk of thromboembolic complications in patients with atrial fibrillation (AF), and warfarin is the medication most frequently used. However, nonadherence associated with OA medications may lead to considerable health risks. A conceptual model of OA medication adherence in patients with AF could clarify factors affecting adherence, thereby assisting in the development and structuring of adherence-promotion programs. To our knowledge, such a model, driven by information obtained directly from patients, has never been developed. OBJECTIVES: To develop a conceptual model of adherence to OA medication based on a literature review and patient feedback via qualitative research among patients with AF. METHODS: A literature search was conducted of English-language articles published between the years 2005 and 2010 that related to factors affecting OA medication adherence, excluding articles pertaining to AF associated with mechanical heart valve replacement. To expand on the literature review findings, 4 focus groups totaling 38 participants aged 60 years or older, diagnosed with nonvalvular AF, and currently taking any OA medication were conducted in 2011. Participants completed the Modified Morisky Scale (MMS), with subscales measuring motivation and knowledge, and were asked about daily processes and behaviors related to taking OA medication. The identification of focus group themes was based on the frequency of participant report and endorsement; themes were spontaneously mentioned or supported by at least 2 people in each of at least 3 focus groups. Model concepts, based on focus group themes and factors identified in the literature review, were determined by the consensus of 3 authors. RESULTS: 181 publications were identified; 30 were selected for full-text review. The focus group participants had a mean age of 69.9 years. Most participants reported a diagnosis of hypertension (86.8%, n = 33), high cholesterol (50.0%, n = 19), heart disease or chronic heart failure (31.6%, n = 12), or diabetes (28.9%, n = 11). Most (89.5%, n = 34) were taking warfarin. About one-half (52.6%, n = 20) had been taking an OA medication for less than 5 years. On the MMS, 78.9% of participants reported high levels of motivation, and 100% reported high levels of knowledge. Four concepts emerged from the focus groups and were supported by the literature for inclusion in the model: (a) knowledge base of the disease and continued reinforcement (i.e., health care professional reinforcement); (b) short-term and long-term motivation (e.g., avoidance of negative health consequences); (c) personalized system, habit formation, and system adaptation (e.g., developing a routine or external reminders); and (d) self-efficacy loop (i.e., the personalized system and its adaptability are reinforced as patients become more consistent, confident, and adherent). The literature review also suggested other factors that may also affect patient adherence (e.g., demographic, psychosocial, cognitive). CONCLUSIONS: Adherence in patients with AF is complex and involves multiple factors, some specific to each individual and others more general. This model identifies an adherence process that can guide opportunities for effective interventions, such as educational and behavioral programs targeted at these processes, to improve patient adherence to OA medication.