In conducting a systematic review, it is important that you search widely through published and unpublished research, to find all information available on a particular topic. This usually includes searching sources such as:
The databases you choose to search will depend on the topic of your systematic review. It is important to search a range of multidisciplinary and subject specific databases.
The Library provides access to important health databases such as the ones below. A comprehensive list is accessible via the Library’s Databases page.
More information on database searching, including a list of subject specific databases can be found in:
Why are the results of trials important to consider?
It is important that all healthcare decisions are informed by all available evidence, thus overcoming publication bias and selective reporting. The data contained in clinical trials that are unpublished or ongoing, can provide important additional clinical evidence.
Development of trial registers
In the past decade mandates around registration of trials has increased their retrievability in trial registers. There is increasing acceptance on behalf of investigators of the importance of registering trials at inception and unwillingness of leading medical journal publishers to publish reports of trials not properly registered. Cochrane Handbook (Part 2, 4.3.3).
No single resource gives access to all trials, and multiple registers should be searched as broadly as possible. Examples include:
Further discussion on this topic can be found in the article below:
Hunter, K, Webster, A, Page, M, Willson, M, McDonald, S, Berber, S et al. Searching clinical trials registers: guide for systematic reviewers. BMJ. 2022; 377 :e068791. https://doi.org/10.1136/bmj-2021-068791
Isojarvi, J, Wood, H, Lefebvre, C, Glanville, J. Challenges of identifying unpublished data from clinical trials: Getting the best out of clinical trials registers and other novel sources. Res Syn Meth. 2018; 9: 561– 578. https://onlinelibrary.wiley.com/doi/10.1002/jrsm.1294
Searching the following guidelines may also be useful:
“Handsearching involves a manual page-by-page examination of the entire contents of a journal issue or conference proceedings to identify all eligible reports of trials. In journals, reports of trials may appear in articles, abstracts, news columns, editorial, letters or other text” (Cochrane Handbook, 6.2.2.1)
Why is handsearching important?
For the trials that are reported, they may not be easily identified as trials due to indexing issues associated with some databases
Note: Conference proceedings are important to hand search because individual conference papers are rarely indexed.
For more information, refer to:
Handsearching (4.S1 Technical Supplement, 1.3.1)
Searching the reference lists of various sources such as those listed below may also be useful as they could provide information on other studies and search strategies used.
Citation searching is an important addition to database searching and handsearching. It can help you tract a particular study over a period of time - allowing you to follow the the study both forward and backward in time, to see if they are relevant to your review.
To do this, search for a key article, then use the database’s functionality to link to citations and references for that article.
Citation databases:
A multidisciplinary citation database
A multidisciplinary citation database of peer-reviewed literature. It includes journals indexed in MEDLINE.