Systematic reviews are at the top of the evidence pyramid. It is the search and synthesis of available evidence to answer a clear and objective scientific question, through systematic and reproducible methods for identifying and selecting relevant primary studies, as well as extracting and analyzing the data reported in these studies.

The first step in the development of a systematic review is the formulation of a scientific question based on the acronym PICOS, which aims to clarify the population of interest, the evaluated intervention, its comparators, the important outcomes and the type of study that is intended to identify. From the PICOS, search strategies are developed that help to search the studies of interest in the literature bases. After selecting the studies and extracting the results, the systematic review may or may not be followed by a meta-analysis, which uses statistical methods to synthesize the collected results.

The systematic review aims to carry out a critical and comprehensive review of a given subject. It is a key tool for developing HTA dossiers, consensus and clinical guidelines, and for establishing the clinical journey for each clinical condition.