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Observational Studies: Cohort and Case-Control Studies

Song, Jae W. M.D.; Chung, Kevin C. M.D., M.S.

Plastic and Reconstructive Surgery: December 2010 - Volume 126 - Issue 6 - p 2234-2242
doi: 10.1097/PRS.0b013e3181f44abc
Special Topics: EBM Special Topic/Outcomes Article

Summary: Observational studies constitute an important category of study designs. To address some investigative questions in plastic surgery, randomized controlled trials are not always indicated or ethical to conduct. Instead, observational studies may be the next best method of addressing these types of questions. Well-designed observational studies have been shown to provide results similar to those of randomized controlled trials, challenging the belief that observational studies are second rate. Cohort studies and case-control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. In this review article, the authors describe these study designs and methodologic issues, and provide examples from the plastic surgery literature.

Ann Arbor, Mich.

From the Section of Plastic Surgery, Department of Surgery, University of Michigan Health System.

Received for publication January 27, 2010; accepted March 5, 2010.

Disclosure:The authors have no financial interest to declare in relation to the content of this article.

Kevin C. Chung, M.D., M.S.; Section of Plastic Surgery; University of Michigan Health System; 1500 East Medical Center Drive; 2130 Taubman Center, SPC 5340; Ann Arbor, Mich. 48109-5340;

©2010American Society of Plastic Surgeons