In contrast to the traditional literature review, systematic literature reviews use a more rigorous and precise approach to reviewing the literature in a specific subject area.
What are systematic reviews? Prepared by the Cochrane Consumers and Communication Group
Researchers conducting a systematic review need to follow fixed yet flexible and iterative processes that describe necessary steps required to produce a rigorous synthesis of the literature.
You should document at the time all of the steps that you take to complete your review, as this allows your methodology to be compiled accurately.
It is vital to define your question and determine if any other systematic review has previously been conducted on this question. To reduce bias in a systematic review, it is vital to develop a review plan or protocol.
Source: Foster, M.J. and Jewell, S.T. (eds.), 2017. Assembling the pieces of a systematic review: a guide for librarians.
Before starting, it’s important to ensure that your research question has not already been successfully answered in a recent review, and that no reviews on the topic are planned or in progress. Reviews in progress (or prospective systematic reviews) may be referred to as protocols. A protocol clearly documents what the reviewers intend to do in their systematic review.
Protocols are used to pre-establish objectives and methods for your systematic review. They should be established prior to the formal literature search to help decrease bias. Registering protocols is recommended to avoid duplication of effort. Once you've developed your protocol, register it!
PROSPERO is the International prospective register of systematic reviews in health and social care, welfare, public health, education, crime, justice, and international development. (Cochrane protocols are automatically uploaded to Prospero).
Systematic reviews should be transparent and replicable, you are required to document each step as you progress. There is no one way to do this! Possibilities include using Excel or Word, keeping a journal, and creating personal database accounts for saving searches as you proceed.
Data collected should be accurate, complete, and in a format that allows for future updates and data sharing. We recommend using bibliographic software like EndNote Online.
As with any data collection and reporting process, it's worthwhile keeping in mind basic data management principles:
See: Research Data Management for more information.
Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. PRISMA focuses on the reporting of reviews evaluating randomized trials, but can also be used as a basis for reporting systematic reviews of other types of research.
Checkout the PRISMA resources:
There is no set number of resources to search; you need to ensure that the search is expansive and comprehensive and include published and (in most cases) unpublished sources. Best practice is to search more than one resource. Systematic reviews in health and medicine will often search 3-5 databases, and searching more is not unusual.
Start with identifying the key databases covering your subject area by taking a look at the databases on the appropriate subject guide, or by going directly to our Databases A-Z. Your Subject Librarian can also advise on the best ones to search.
Search Smart is a free online guide to researchers best search options
Developing a search strategy is the process of converting your research question into a format that the database can interpret. Databases work by matching the search terms that you enter to the titles, abstracts, and subject headings in the records of items in the database. To locate the relevant literature, you need to use the same terms that are used in relevant sources.
For each identified concept in your research question, make a list of relevant keywords and subject headings. Once you have identified your key concepts, identify the words most likely to have been used in the published literature on this topic. It is important to develop a comprehensive range of terms for each discrete concept entailing a combination of subject headings and a wide range of keywords/phrases for each concept. It’s crucial to develop clear inclusion and exclusion criteria.
Create and test your search strategy in a primary database, then move on to running the search in other databases you've selected for your review.
The official guide that describes in detail the process of preparing and maintaining Cochrane systematic reviews on the effects of healthcare interventions. By Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane, 2023.
JBI is an international evidence-based healthcare research organisation. This manual is a comprehensive guide to conducting JBI systematic reviews. It describes in detail the process of planning, undertaking and writing up a systematic review using JBI methods.
It is common to confuse systematic and literature reviews as both are used to provide a summary of the existing literature or research in a specific area.
Table from: Robinson, P. and Lowe, J., 2015. Literature reviews vs systematic reviews. Australian and New Zealand journal of public health, 39(2), pp.103-103. https://doi.org/10.1111/1753-6405.12393
For information on other types of reviews see: A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108. doi:10.1111/j.1471-1842.2009.00848.x
Your subject librarian is available to consult with researchers and offer training to:
External training: Evidence Synthesis Ireland (ESI) Training & Webinars