This handbook provides a concise compilation of the evidence supporting diagnostic testing and clinical decision rules in emergency care. Clinical decision rules are now widely recognized as best practice for the ordering of diagnostic tests in the emergency department. Aimed at all physicians working with emergency and acute patients, the book begins with an overview of how to evaluate a diagnostic test using an evidence-based approach, followed by an explanation of the clinical decision rules and the methods of assessing the strength and applicability of the clinical prediction rule. For each test and clinical decision rule, the most current and best available studies in the literature are discussed and applied to emergency department and acute care patients in addressing the question at hand, followed by an overall recommendation on how to use the test or rule in the clinical context. This book is an accessible and extremely useful reference for physicians at all levels to use in applying an evidence-based approach to ordering and interpreting tests in an acute care environment.