Specific inclusion criteria ensure that the included studies will meet these criteria and they represent an important and transparent plan for to the selection of studies for the review. The inclusion criteria are also critical when formulating a comprehensive search strategy to locate studies.
Authors will realize that the traditional PICO format (Population, Intervention, Comparator, Outcomes) commonly encountered and well aligned to systematic reviews assessing the effectiveness of interventions or therapies in health care does not readily align with questions relating to etiology and risk (The Joanna Briggs Institute a, 2014). Rather, a systematic review of etiology should include the following components, easily referred to as PEO: