Systematic Review: What it is and isn't
What it is
Simply put, a systematic review is a summary of all research, published and unpublished, on a particular topic. Systematic reviews, as a form of research, emerged as a necessary response to two main factors: the explosion in the amount of published medical literature, and the inadequacies of traditional review articles.
As the volume of medical literature continues to grow, it becomes ever more difficult to keep up with and make sense of research, particularly when it shows contradictory or unclear results when viewed in isolation from one another.1
Traditional reviews have employed a method that has not been as rigorous as necessary when evaluating the evidence, which can unfortunately lead to the possibility of bias in the review.
A systematic review is intended to overcome each of these issues. A systematic review is designed to bring together all research on a topic by conducting a thorough literature search. The resulting body of research from these searches is reviewed for inclusion/exclusion and the included studies are then critically appraised and reported in an unbiased way. In other words, they are conducted with the same methodological rigor as primary studies.2
A systematic review generally involves the following eight steps:
Following the conditions of each step results in a review that is a summary of the best evidence available for the research question posed. Although time consuming and expensive, they provide a summary of what we know about a topic or a recommendation for further research.
If the systematic review is to be submitted to a journal, be sure to check the journal’s ‘Author Instructions’ for details on their specific requirements and any evaluative tools they may recommend. Different journals may vary in the rigor they require for a systematic review submission, however, a complete systematic review would generally involve most, if not all, of the steps noted above.
What it isn't
A systematic review is not a narrative description of some research in a particular area or an opinion piece based on a portion of the literature. Even a comprehensive literature review may not qualify as a systematic review if it does not have a clear research question and a well developed research protocol.
There are also other types of reviews that you may come across in the literature. They include such things as scoping reviews, narrative reviews, meta-ethnographies, realist synthesis, and so on. For more information on these types of reviews, we invite you to take a look as some of the resources on these methods compiled by the Canadian Institute of Health Research (CHIR).
A Thorough Example
The following citation takes you to an extremely thorough example of a completed systematic review, that includes all the steps involved in a systematic review, with all the tables and assessments:
Ensing HT, Stuijt CC, van den Bemt BJ, van Dooren AA, Karapinar-Çarkit F, Koster ES, Bouvy ML. Identifying the Optimal Role for Pharmacists in Care Transitions: A Systematic Review. J Manag Care Spec Pharm. 2015 Aug;21(8):614-36. Review. PubMed PMID: 26233535. DOI: 10.18553/jmcp.2015.21.8.614 [Free full text]