Evidence-based medicine in surgery is essential to the delivery of high-quality care. Comparative effectiveness research (CER) using observational study designs refers to the wide scope of research that allows for the generation of evidence to support one care strategy over another. Comparative effectiveness research is defined by the Institute of Medicine as the 鈥済eneration and synthesis of evidence that compares the benefits and harms of alternative methods to prevent, diagnose, treat, and monitor a clinical condition or to improve the delivery of care.鈥�¹ The purpose of CER is to provide actionable evidence to consumers, clinicians, purchasers, and policy makers to make informed decisions.¹