Evidence-Based Medicine in Surgery:  The Importance of Both Experimental and Observational Study Designs

The Institute of Medicine defines the quality of health care as the “degree to which health services for individuals and populations increase the likelihood of desired health outcomes and are consistent with current professional knowledge.”¹ Yet for much of the 20th century, the knowledge base for surgical practice was not influenced by systematic evidence, but rather by expert opinion and collective experience. Early attempts to scientifically measure and improve surgical quality, such as Codman's “end result idea”² in the early 1900s that sought to collect and analyze surgical outcomes, met intense resistance. Fortunately, evidence-based medicine in surgery has now been thoroughly accepted; sophisticated researchers are applying a variety of study designs and methodological techniques to answer an expansive number of important clinical questions. Nonetheless, despite the diversity of high-quality research being performed, many continue to contend that the randomized controlled trial (RCT) is the only valid source of evidence, whereas observational research is assumed to be only preliminary work. The need and legitimacy of both experimental and observational studies deserve to be highlighted.