· Home  · Overall Schedule   · Courses  · Programs  · Rosters  · Career Awards

PREFACE

This is a book about diagnostic testing. It is aimed primarily at clinicians, particularly those who are academically minded, but it should be helpful and accessible to anyone involved with selection, development, or marketing of diagnostic, screening, or prognostic tests. Although we admit to a love of mathematics, we have restrained ourselves and kept the math to a minimum — a little simple algebra and virtually no Greek letters. Nonetheless, quantitative discussions in this book go deeper and are more rigorous than those typically found in introductory clinical epidemiology or evidence-based medicine texts.

Our perspective is that of skeptical consumers of tests. We want to make proper diagnoses and not miss treatable diseases. Yet, we are aware that vast resources are spent on tests that too frequently provide wrong answers or right answers of little value, and that new tests are being developed, marketed, and sold all the time, sometimes with little or no demonstrable or projected benefit to patients. This book is intended to provide readers with the tools they need to evaluate these tests, decide if and when they are worth doing, and interpret the results.

The pedagogical approach comes from years of teaching this material to physicians, mostly fellows and junior faculty in a clinical research training program. We have found that many doctors, including the two of us, can be impatient when it comes to classroom learning. We like to be shown that the material is important and that it will help us take better care of our patients, understand the literature, and improve our research. For this reason, in this book we emphasize real-life examples. When we care for patients and read journal articles, we frequently identify issues that the material we teach can help people understand. We have decided what material to include in this book largely by creating homework problems from patients and articles we have encountered, and then making sure that we covered in the text the material needed to solve them. This explains the disproportionate number of pediatric and emergency medicine examples, and the relatively large portion of the book devoted to problems and answers — the parts we had the most fun writing.

Although this is primarily a book about diagnosis, two of the 12 chapters are about evaluating treatments - both using randomized trials (Chapter 9) and observational studies (Chapter 10). The reason is that evidence-based diagnosis requires not only being able to evaluate tests and the information they provide, but also the value of that information - how it will affect treatment decisions, and how those decisions will affect patients' health. For this reason, the chapters about treatments emphasize quantifying risks and benefits. Other reasons for including the material about treatments, which also apply to the material about P-values and confidence intervals in Chapter 11, are that we love to teach it, have lots of good examples, and are able to focus on material neglected (or even wrong) in other books.

After much deliberation, we decided to include answers to all of the problems. However, we strongly encourage readers to think about, and even write out the answers to the problems before looking at the answers at the back of the book. The disadvantage of including all of the answers is that instructors wishing to use this book for a course will have to create new problems for any take-home or open-book examinations. Since that includes us, we will continue to write new problems, and will be happy to share them with others who are teaching courses based on this book. We will post the additional problems on the book's website, www.epibiostat.ucsf.edu/ebd. Several of the problems in this book are adapted from problems our students created in our annual final examination problem-writing contest. Similarly, we encourage readers to create problems and share them with us. With your permission, we will adapt them for the second edition!