Chapter 1: Introduction

Introduction Example A 51-year-old man asks to see you because of chest pain that he thinks is “indigestion.” He was well until 2 weeks ago, when he noticed tightness in the center of his chest after a large meal and while walking uphill. The tightness stopped after 2 to 3 minutes of rest. A similar […]

Chapter 2: Frequency

Introduction Chapter 1 outlined the questions that clinicians need to answer as they care for patients. Answers are usually in the form of probabilities and only rarely as certainties. Frequencies obtained from clinical research are the basis for probability estimates for the purposes of patient care. This chapter describes basic expressions of frequency, how they […]

Chapter 3: Abnormality

Introduction inicians spend a great deal of time distinguishing “normal” from “abnormal.” Is the thyroid normal or slightly enlarged? Is the heart murmur “innocent” (of no health importance) or a sign of valvular disease? Is a slightly elevated serum alkaline phosphatase evidence of liver disease, unrecognized Paget disease, or nothing important? When confronted with something […]

Chapter 4: Risk: Basic Principles

Introduction Risk generally refers to the probability of some untoward event. In medicine, clinicians deal with probabilities in virtually every patient encounter. They work with basic principles of risk whether they are diagnosing a complaint, describing prognosis, deciding on treatment, or discussing prevention with the patient. Patient encounters no longer deal only with the patient’s […]

Chapter 5: Risk: Exposure to Disease

Studies of Risk This chapter describes how investigators obtain estimates of risk by observing the relationship between exposure to possible risk factors and the subsequent incidence of disease. It describes methods used to determine risk by following groups into the future and also discusses several ways of comparing risks as they affect individuals and populations. […]

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. […]

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 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 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 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 […]