For studies that did not report the proportion of strokes that were fatal and nonfatal, we used all available data in the published report to obtain a best estimate of the effect of The article ends with a discussion of practical issues in the use of adjusted-dose vitamin K antago- nist (VKA) therapy in patients with AF and sugges- tions for future research. Table 1 speci es the clinical question being addressed in this article (in PICO [population, inter- vention, comparator, outcomes] format) and the types of studies used. This article does not give recommen- dations for antithrombotic therapy in patients with AF around the time of surgical or invasive proce- dures (see Douketis et al5), at the time of presen- tation with acute stroke (see Lansberg et al6), or in patients with AF who have prosthetic heart valves (see Whitlock et al7). This article does not give recom- mendations for patients with AF who are pregnant. For general recommendations on antithrombotic ther- apy during pregnancy (ie, not speci c to AF), see Bates et al.8 Finally, the recommendations in this article apply to patients with persistent and perma- nent AF and to patients with PAF but do not apply to patients with a single, transient, self-limited episode of AF associated with acute illness. To inform our guideline development, we searched for relevant articles published since the last literature search performed for the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Speci cally, for literature regarding the assess- ment of stroke risk in patients with AF, we searched Medline for articles published from January 1, 2005, to October 2009 using the search terms atrial brillation, atrial utter, risk assess- ment, risk factors, risk strati cation, stroke, and thrombo- embolism. 