The levels of evidence and their role in evidence-based medicine.

As the name suggests, evidence-based medicine (EBM), is about finding evidence and using that evidence to make clinical decisions. A cornerstone of EBM is the hierarchical system of classifying evidence. This hierarchy is known as the levels of evidence. Physicians are encouraged to find the highest level of evidence to answer clinical questions. Several papers published in Plastic Surgery journals concerning EBM topics have touched on this subject. Specifically, previous papers have discussed the lack of higher level evidence in PRS and need to improve the evidence published in the journal. Before that can be accomplished, it is important to understand the history behind the levels and how they should be interpreted. This paper will focus on the origin of levels of evidence, their relevance to the EBM movement and the implications for the field of plastic surgery as well as the everyday practice of plastic surgery.