The Impact of Level II Evidence on Surgical Practice: Dual Agent Bowel Prep for Elective Colorectal Surgery.

Retrospective cohort studies are the most commonly published and cited original articles in major surgical journals.1 Ideally, level I evidence guides clinical decision-making, but randomized trials are expensive, resource-consuming, and at times impractical. In these settings, findings from well-designed retrospective cohort studies represent the next best option.2 Improvements in retrospective cohort studies are often dependent on data reliability, and the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) offers high-quality data about surgical patients from across the US.