A systematic review can be defined as a "scientific investigation that focuses on a specific question and uses explicit, prespecified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies."¹⁾ Systematic reviews aim to minimize bias by using explicit and systematic methods. To reach such a goal, systematic reviews seek to collate all evidence that fits pre-specified eligibility criteria in order to address a specific research question. The key characteristics of a systematic review are 1) a clearly stated set of objectives with pre-defined eligibility criteria for studies; 2) explicit, reproducible methodology; 3) a systematic search that attempts to identify all studies that would meet the eligibility criteria; 4) an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias; and 5) a systematic presentation, and synthesis, of the characteristics and findings of the included studies.²⁾