This guide aims to support all OHSU members' systematic review education and activities, orienting OHSU members who are new to systematic reviews and facilitating the quality, rigor, and reproducibility of systematic reviews produced by OHSU members.
In it you will find:
"A systematic review is a summary of the medical literature that uses explicit and reproducible methods to systematically search, critically appraise, and synthesize on a specific issue. It synthesizes the results of multiple primary studies related to each other by using strategies that reduce biases and random errors."
Gopalakrishnan S, Ganeshkumar P. Systematic Reviews and Meta-analysis: Understanding the Best Evidence in Primary Healthcare. J Family Med Prim Care. 2013;2(1):9-14. doi:10.4103/2249-4863.109934
Systematic Reviews are a vital resource used in the pursuit of Evidence-Based Practice (EBP):
Research design and evidence, by CFCF, CC BY-SA 4.0, via Wikimedia Commons
Things to know about systematic reviews:
The practice of producing systematic reviews is sometimes referred to by other names such as:
This guide tries to stick with the term "Systematic Reviews" unless a specific type of systematic review is being discussed.
While all reviews combat information overload in the health sciences by summarizing the literature on a topic, different types of reviews have different approaches. The term systematic review is often conflated with narrative literature reviews, which can lead to confusion and misunderstandings when seeking help with conducting them. This table helps clarify the differences.
| Systematic Reviews | Narrative Literature Reviews | |
|---|---|---|
| Authors | Two or more authors are involved in good quality systematic reviews, many comprise multiple authors with expertise in the different stages of the review | One or more authors, usually experts in the topic of interest |
| Study Protocol | Written study protocol which includes details of the methods to be used | No study protocol |
| Research Question |
Specific question which may have all or some of PICOTS components (Population, Intervention, Comparator, Outcome, Time, and Setting) Hypothesis is clearly stated |
Broad to specific question, hypothesis typically not stated |
| Search Strategy | Detailed and comprehensive search strategy is developed, preferably utilizing the skills of an experienced librarian | No detailed search strategy, supporting literature search is probably conducted using general keyword queries |
| Sources of Literature |
List of databases, websites and other sources of included studies are listed Both published and unpublished literature are considered |
Not usually stated and non-exhaustive, featured articles often already known to the authors Prone to publication bias |
| Selection Criteria | Specific inclusion and exclusion criteria for evaluating abstracts and articles are described | No specific selection criteria, usually subjective Highly prone to selection bias |
| Critical Appraisal | Rigorous appraisal of study quality and methodology | Variable evaluation of study quality or method |
| Synthesis | Narrative, quantitative, and/or qualitative synthesis techniques are used | Often only qualitative synthesis of evidence |
| Conclusions | Conclusions drawn are evidence based | Sometimes evidence based, but can be significantly influenced by author’s personal beliefs and biases and its conclusions may be highly subjective |
| Reproducibility | Accurate documentation of methods means process can be repeated | Undocumented or incomplete methodology means findings cannot be reproduced independently |
| Updates | Systematic reviews can be periodically updated to include new evidence | Cannot be accurately updated |
