Educational and behavioural interventions for anticoagulant therapy in patients with atrial fibrillation

Abstract

Atrial Fibrillation (AF) is the most common arrhythmia in clinical practice (Fuster 2006) and is associated with a five-fold greater risk of stroke and thromboembolism (Wolf 1991). Prevalence of AF increases with age (Kannel 1998), from 1.5% at age 50-59 years to 23.5% at age 80-89 years (Wolf 1998), as does the incidence of stroke attributable to AF (Lip 2006a). The lifetime risk of developing AF is approximately one in four among people aged 40 years and older (Lloyd-Jones 2007). Assessment of thromboembolic risk determines subsequent treatment plans. There are many stroke risk-stratification models (Stroke Risk in AF Working Group 2007), derived from pooled analysis from the data of antithrombotic treatment trials. The models vary in complexity, but four key clinical features are consistently identified as independent risk factors for stroke: prior stroke or TIA, older age (≥ 75), hypertension, and diabetes mellitus. The CHADS2 (Gage 2001) stroke risk stratification scheme is simple and well validated scheme, and is the most widely employed. The acronym CHADS2 stands for each of the risk factors: congestive heart failure, hypertension, aged ≥ 75 years, diabetes mellitus (for which one point is given for each risk factor present), and previous stroke/TIA (which receives two points). Thus the total score ranges from 0 to six. In the United Kingdom, AF patients are risk stratified for stroke using the NICE guidelines (NICE 2006). The NICE guidelines are a practical algorithm based risk stratification. These evidence-based guidelines stratify patients into low, moderate and high risk categories and have similar predictive value for stroke and other vascular events to the CHADS2 scheme (Lip 2006b).