Appendix: Answers to Review Questions

Chapter 1 Introduction 1.1. D. Samples can give a misleading impression of the situation in the parent population, especially if the sample is small. 1.2. E. Generalizing the results of a study of men to the care of a woman assumes that the effectiveness of surgery for low back pain is the same for men […]

Chapter 14: Knowledge Management

Introduction Finding the best available answer to a specific clinical question is like finding a needle in a haystack. Essential information is mixed with a vast amount of less credible “factoids” and opinions, and it is a daunting task to sort the wheat from the chaff. Yet, that is what clinicians need to do. Critical […]

Chapter 13: Summarizing the Evidence

Introduction Clinical decisions are based on the weight of evidence bearing on a question. Sometimes the results of large, strong studies are so compelling that they eclipse all other studies of the same question. More often, however, clinicians depend on the accumulation of evidence from many less definitive studies. When considering these individual studies, clinicians […]

Chapter 12: Cause

Introduction This book has been about three kinds of clinically useful information. One is description, a simple statement of how often things occur, summarized by metrics such as incidence and prevalence, as well as (in the case of diagnostic test performance) sensitivity, specificity, predictive value, and likelihood ratio. Another is prediction, evidence that certain outcomes […]

Chapter 11: Chance

Introduction Learning from clinical experience, whether during formal research or in the course of patient care, is impeded by two processes: bias and chance. As discussed in Chapter 1, bias is systematic error, the result of any process that causes observations to differ systematically from the true values. Much of this book has been about […]

Chapter 10: Prevention

Introduction Most doctors are attracted to medicine because they look forward to curing disease. But all things considered, most people would prefer never to contract a disease in the first place—or, if they cannot avoid an illness, they prefer that it be caught early and stamped out before it causes them any harm. To accomplish […]

Chapter 9: Treatment

Introduction After the nature of a patient’s illness has been established and its expected course predicted, the next question is, what can be done about it? Is there a treatment that improves the outcome of disease? This chapter describes the evidence used to decide whether a well-intentioned treatment is actually effective. Ideas and Evidence The […]

Chapter 8: Diagnosis

Introduction Clinicians spend a great deal of time diagnosing complaints or abnormalities in their patients, generally arriving at a diagnosis after applying various diagnostic tests. Clinicians should be familiar with basic principles when interpreting diagnostic tests. This chapter deals with those principles. A diagnostic test is ordinarily understood to mean a test performed in a […]

Chapter 7: Prognosis

Introduction When people become sick, they have a great many questions about how their illness will affect them. Is it dangerous? Could I die of it? Will there be pain? How long will I be able to continue my present activities? Will it ever go away altogether? Most patients and their families want to know […]

Chapter 6: Risk: From Disease to Exposure

Introduction Cohort studies are a wonderfully logical and direct way of studying risk, but they have practical limitations. Most chronic diseases take a long time to develop. The latency period, the period of time between exposure to a risk factor and the expression of its pathologic effects, is measured in decades for most chronic diseases. […]