Traditionally, case-control studies have been viewed as an alternative to cohort studies in which individuals were selected on the basis of whether or not they had the disease outcome of interest, with investigators then comparing exposure history between those with the disease (the cases) and those free of the disease (the controls). More recently, the theory behind the case-control study has been re-imagined as a method of selecting a subset of an underlying cohort giving rise to the cases in the study. The case-control study design is an excellent choice of study when the disease is rare, has a long induction period , the exposure data are difficult to obtain, or very little is known about the disease. In these situations a cohort study is generally prohibitively expensive or the time frame of the study required for data collection is impractical. Unlike cohort studies, case-control studies identify cases of the disease of interest in their population and then compare their exposure experience to sampled controls. As you will learn in the following exercise, this method is deceptively simple, and if not planned carefully, can lead to spurious findings.

Faculty Highlight: Dr. Alfred Neugut

"The case-control study's simplicity sometimes makes us forget just how elegant and revolutionary a creation it was of 20th century chronic disease epidemiology."

Dr. Neugut is a Professor of Medicine and the Myron M. Studner Professor of Cancer Research. His research interests span the epidemiology and screening of colorectal neoplasia, breast cancer etiology and treatment, racial disparities in cancer, and cancer in the elderly. He serves as co-PI of the Long Island Breast Cancer Study, a large population-based case-control study.

Read more about Dr. Neugut's work

• Terry MB, Gammon MD, Zhang FF, Tawfik H, Teitelbaum SL, Britton JA, Subbaramaiah K, Dannenberg AJ, Neugut AI. Association of frequency and duration of aspirin use and hormone receptor status with breast cancer risk. JAMA. 2004 May 26;291(20):2433-40.
• Hershman D, McBride R, Jacobson JS, Lamerato L, Roberts K, Grann VR, Neugut AI. Racial disparities in treatment and survival among women with early-stage breast cancer. J Clin Oncol. 2005 Sep 20;23(27):6639-46.
• Zablotska LB, Chak A, Das A, Neugut AI. Increased risk of squamous cell esophageal cancer after adjuvant radiation therapy for primary breast cancer. Am J Epidemiol. 2005 Feb 15;161(4):330-7.