Evidence-based Medicine

Introduction

This fifth article in the evidence-based medicine (EBM) series integrates the first three steps of EBM introduced previously (asking an answerable question, searching the literature, critical evaluation of the literature) into a fourth step that applies valid evidence discerned in those steps to medical decision-making. Integration of EBM with medical decision-making constitutes the foundation of what has been termed evidence-based practice (EBP). By definition, EBP is the integration of best research evidence with patient values and clinical circumstances to make clinical decisions. (1) Developing an EBP involves conscientious decision-making based on evidence combined with knowledge of patient characteristics, situations, and preferences, and requires three additional tasks:

• Define the problem

• Identify a rational differential diagnosis

• Develop an action plan

This contribution to the EBM series applies previously introduced components from the EBM tool box to convert a problem presented by a patient into a set of rational diagnoses. Additional tools are used for judicious selection of diagnostic testing that prioritizes the diagnoses effectively. Finally, methodology that allows the choice of a definitive action plan is described so a clear decision point can be reached confidently, once a single working diagnosis is given priority. A case referred by an otolaryngologist for preoperative clearance illustrates these points.

A 4-year-old girl scheduled for tonsilloadenoidectomy has a history of chronic rhinitis, pharyngitis, and recurrent epistaxis. Family history reveals a grandfather who has type I von Willebrand disease (vWb). Physical examination of the girl reveals multiple bruises in various stages of resolution.

Step 1: Define the Problem

The question posed by the surgeon is, “Can you clear this patient for surgery?” The process of defining a problem begins by rephrasing the surgeon's question into a question whose answer facilitates achievement of the real goal, which is to minimize surgical risk. The best initial problem-defining EBM question becomes, “What is the likelihood …