Systematic Reviews are defined as scientific investigations that attempt to answer focused questions and present pre-planned strategies to include all relevant articles, appraise primary trials and synthesize data, making an effort to reduce bias.

Meta-Analysis is defined as a statistical synthesis of data obtained from original research articles previously gathered by means of a systematic review in which data are comparable.

Systemic Review and Meta-Analysis are the highest level of scientific evidence and may strengthen clinically useful evidence.

Systematic Reviews and/or Meta-Analysis should be based on a focused question, ideally intended to solve a clinical problem. This question may be described in a PICO/PECO format (Patient/Problem/Population; Intervention/Exposure; Comparison and Outcomes).