Most of us are familiar with the terms systematic review and literature review. Both review types synthesize evidence and provide summary information. So what are the differences? What does systematic mean? And which approach is best ?
‘Systematic‘ describes the review’s methods. It means that they are transparent, reproducible and defined before the search gets underway. That’s important because it helps to minimize the bias that would result from cherry-picking studies in a non-systematic way.
Literature reviews don’t usually apply the same rigor in their methods. That’s because, unlike systematic reviews, they don’t aim to produce an answer to a clinical question. Literature reviews can provide context or background information for a new piece of research. They can also stand alone as a general guide to what is already known about a particular topic.
Let’s take a look at the two review types in more detail to highlight some key similarities and differences.
What is a systematic review?
Systematic reviews ask a specific question about the effectiveness of a treatment and answer it by summarizing evidence that meets a set of pre-specified criteria.
The process starts with a research question and a protocol or research plan. A review team searches for studies to answer the question using a highly sensitive search strategy. The retrieved studies are then screened for eligibility using the inclusion and exclusion criteria (this is done by at least two people working independently). Next, the reviewers extract the relevant data and assess the quality of the included studies. Finally, the review team synthesizes the extracted study data and presents the results.
The results of a systematic review can be presented in many ways and the choice will depend on factors such as the type of data. Some reviews use meta-analysis to produce a statistical summary of effect estimates. Other reviews use narrative synthesis to present a textual summary.
When is it appropriate to do a systematic review?
If you have a clinical question about the effectiveness of a particular treatment or treatments, you could answer it by conducting a systematic review. Systematic reviews in clinical medicine often follow the PICO framework, which stands for:
Here’s a typical example of a systematic review title that uses the PICO framework:
Alarms [intervention] versus drug treatments [comparison] for the prevention of nocturnal enuresis [outcome] in children [population]
Key attributes
What is a literature review?
Literature reviews provide an overview of what is known about a particular topic. They evaluate the material, rather than simply restating it, but the methods used to do this are not usually prespecified and they are not described in detail in the review. The search might be comprehensive but it does not aim to be exhaustive. Literature reviews are also referred to as narrative reviews.
Literature reviews use a topical approach and often take the form of a discussion. Precision and replicability are not the focus, rather the author seeks to demonstrate their understanding and perhaps also present their work in the context of what has come before. Often, this sort of synthesis does not attempt to control for the author’s own bias. The results or conclusion of a literature review is likely to be presented using words rather than statistical methods.
When is it appropriate to do a literature review?
We’ve all written some form of literature review: they are a central part of academic research. Literature reviews often form the introduction to a piece of writing, to provide the context. They can also be used to identify gaps in the literature and the need to fill them with new research.
Key attributes
What is a systematic literature review?
Systematic review methodology has its roots in evidence-based medicine but it quickly gained traction in other areas – the social sciences for example – where researchers recognize the value of being methodical and minimizing bias. Systematic review methods are increasingly applied to the more traditional types of review, including literature reviews, hence the proliferation of terms like ‘systematic literature review’ and many more.
Conclusion
Review methods are evolving constantly as researchers find new ways to meet the challenge of synthesizing the evidence. Systematic review methods have influenced many other review types, including the traditional literature review.
https://www.covidence.org/blog/the-difference-between-a-systematic-review-and-a-literature-review/
