Crohn's Disease: The Complete Guide to Medical Management

Gary R. Lichtenstein, MD, FACP, FACG, AGAF

Chapter 2: Clinical Research in Inflammatory Bowel Disease: Placebo Response in Clinical Trials (continued)

Chinyu Su, MD; James D. Lewis, MD, MSCE

Clinical research can be divided into descriptive and analytic studies. Descriptive studies include case reports, case series, and analyses of secular trends. The feature that most distinguishes descriptive studies from analytic studies is the lack of a control group. Because there is no control group for comparison, descriptive studies are generally viewed as useful for hypothesis generation but play a small role in proving causality. As will be discussed later in this chapter, uncontrolled studies of drug therapies for IBD (ie, case series) play an important role in selecting medications…