literature review vs systematic review

literature review vs systematic review

Differences between Literature Review and Systematic Review

1. Introduction

Systematic reviews can greatly reduce the time and effort involved in reviewing literature. They adhere to a strict scientific design based on an explicit a priori protocol, where methods are clearly defined to minimize bias. Systematic reviews are an essential tool to support evidence-informed health care, by being able to summarize large quantities of information, and it can provide evidence to answer questions relevant to clinical and policy decision making. With a clear focus on the methods to identify, select and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review. The Cochrane collaboration has been the lead organization to produce systematic reviews of health care. Today systematic reviews are also completed in non-health care sectors, it should be noted that the terminologies and processes may vary between different sectors.

To review academic evidence is to summarize the knowledge of the article materials, to present the way evidence has been gathered and its findings. Literature reviews consist of data that has been available in the public domain and has not been collected using a well-defined, systematic process. Today reviews of literature are more important than ever due to the quantity of articles being published. These reviews serve to inform people in a more condensed and directed way so they can utilize the information, rather than plowing through numerous articles trying to identify what is worthwhile.

2. Purpose of a Literature Review

In order to get through with the problem, there are two approaches often used to gather the information. This is the Literature Review (LR) and Systematic Review (SR). LR and SR might have the general starting point, but the path taken to finish the review in the end might be different. Purposes to LR review might differ than SR, first let us know the exact definition of LR and SR. According to Tranfield et al. (2003), a literature review is a critical and in-depth evaluation of previous research. This can span from the last few decades to recent research. Literature review also can act as a bird’s eye view for the researcher to provide a complete picture of research areas. On the other hand, SR is designed to produce a rigorous and unbiased method of identifying, evaluating, and synthesizing the existing body of completed and recorded work produced in a specific and identifiable area (Grant and Booth, 2009).

3. Purpose of a Systematic Review

It is commonly thought that systematic reviews are only conducted in instances when there is a clear indication for new research i.e. avoid duplication of effort. In reality, systematic reviews are conducted for a number of purposes and can be very valuable in their ability to provide a summary of the current evidence. While one purpose is to indeed inform the need for new research, a systematic review can be conducted to inform policy and decision making where doing further research would be inappropriate. Additionally, as an evidence-based approach to practice becomes increasingly revered, systematic reviews are used as an efficient method to provide a summary for practitioners on current best practice. Systematic reviews are also commonly used to inform patients and can be used to compare the benefits of different treatment options, risk factors or the accuracy of diagnostic tests or measure preventative measures. Finally, one of the most common purposes of a systematic review is to answer a research question. This can be of importance to an academic audience i.e. the purpose to have a review published and be used to inform teaching in a particular discipline or the review could be conducted as a way to reduce bias for a literature review in a new primary research study. A planned review protocol is not solely reserved for reviews with a clinical question and is highly recommended for all types of systematic review.

The overall purpose of a systematic review is to provide a readable (to some extent) comprehensive synthesis of the available primary research on a specific research question. A well-conducted systematic review will provide the strongest possible evidence to support informed decision making and will identify gaps in knowledge. The systematic review methodology provides the framework for evidence-based practice and the review itself can be used to inform clinical guidelines and policy. This article aims to be a contemporary guide for planning, conducting, and evaluating a rigorous systematic review. This is a broad and theoretical perspective of the purpose of a systematic review and we do not aim to cover the specifics of all review types and disciplines in this article.

4. Methodology Differences

Systematic review, on the other hand, is a formalized means of reviewing the literature in a specific area, disease, topic, or theorem. There are various types of systematic reviews: meta-analysis – statistical method of combining data from selected literature to develop a single conclusion that has greater statistical power. Systematic reviews can also be based on quantitative data from studies, the Cochrane Collaboration promotes and disseminates these reviews. Other systematic reviews can be purely qualitative. The aim of a systematic review is to identify, select, and synthesize all of the empirical evidence that fits the pre-specified eligibility criteria in order to answer a specific research question. They often employ the use of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses). This type of review can be of immense help to people who are trying to tackle an ambiguity in their practice, it provides them with a comprehensive summation of evidence on a focused question. By just doing a standardized review one might miss literature of great importance because it is not as visible. Systematic review methodologies have the capacity to bring together an abundance of information that might typically be missed in usual academic reviews. A systematic approach minimizes bias and increases the likelihood of returning a meaningful conclusion. This is done by developing a protocol, which defines the methods for the literature search, appraisal, and synthesis. This protocol acts as a blueprint for the review. The upshot of methodological differences means that literature reviews intend to give a picture of what has been and what is known in a particular area. Systematic reviews aim to inform the reader of the best available information to answer a specific research question. Possible limitations and gaps in the literature will also be identified.

5. Conclusion

A systematic review often has the same intention as this, although a researcher performing a systematic review to evaluate outcomes of health care would develop a research question based on the need for clinical decisions to be made. Usually, a systematic review does not end up getting completed because the extent of research is too vast to cope within the resources of the researchers and funding available. This causes the research question to be adjusted in order to narrow the scope of the review and to specify what is of most importance to the specified audience, often leading to a change in the PICO components (defined in question 2) and better clarification of the review’s purpose. This is somewhat similar to what happens in a literature review, where continued review of the literature can make the original research question or topic hard to define and can cause confusion for the author but excluding irrelevant studies.

Comparatively, a systematic review is used to create an unbiased, valid and reliable method of understanding, interpreting and summarising the data related to the specific research question. This must be done in a way that is transparent and auditable in order to promote the rigour of the methodology (Cooper, 1998). This is contrary to a literature review, where an increasing amount of literature is making the thoroughness of the review very difficult to achieve and what constitutes as “rigour” is often not very well defined by authors. This, however, is of no concern to the author conducting a literature review who simply wishes to integrate what is currently known about a topic in order to address gaps that have been identified.

These two reviews have different aims of the research study. The literature review is an overview of related studies, while a systematic review is an investigation focused on a specific research question. The main purpose of the literature review is to integrate the data available to provide the reason for a research study.