Literature searching skills

Literature searching tutorial
This interactive, online tutorial was designed for undergraduates but will be suitable for anyone who needs an introduction or a refresher on search skills to support assignments and literature reviews in medicine and biomedicine.

• The tutorial sections guide you through the process of doing a literature review; from creating your research question and search strategy, to searching a variety of databases, to exporting and managing the results you find
• Once you are in the tutorial, you can work your way through it sequentially, or use the menu on the left of the screen to go directly to the lesson that you need

The Tutorials, guides and skills page has more resources and support on general literature searching skills and using individual databases.

Systematic review guidance

Systematic review guide and flowchart (pdf)
This flowchart and associated guide supports you through the process of carrying out a systematic review at Imperial College.

• Each box represents a stage in the process of a review from planning to publication, and shows where the Library can assist you throughout the project
• Click on a box to find more guidance and explanations about carrying out each stage
• Appendices contain detailed information and links to further reading and helpful resources
• Contains plenty of information on how to plan and structure your search strategy. You can complement this with our specialist guides on using particular databases on our Tutorials, guides and skills page

Handbooks and official guidance

Links to the Cochrane and Centre for Reviews and Dissemination (CRD) handbooks can be found in our reading list.

Further reading, books and articles

In our reading list you'll also find books and articles offering guidance on systematic reviews and various methodologies.

Systematic review software

Covidence (College resource)
Covidence is a web-based systematic review management platform created in collaboration with Cochrane to manage screening and data collection, for individuals or multiple authors.
Key benefits include:

• Streamlines production of systematic reviews by supporting collaboration and keeping decision making and documentation in one place, safe and easy to access for the whole team
• Students and experienced reviewers alike will find it intuitive to use and it can be used to do a full systematic review or support a literature review done in a systematic manner
• Imperial College users can invite external reviewers (e.g. from an NHS Trust or other university) to be co-reviewers, even if those reviewers don't have access to Covidence via their own institution

The key steps supported by Covidence are:
Import of citations from a range of reference managers and de-duplication of study citations (with manual override), title/abstract level screening, full text review, risk of bias assessment, extraction of study characteristics and outcomes, export of data into RevMan and Excel and of references into reference management software.
Join under Imperial College institutional licence for unlimited reviews.

Systematic Review Toolbox
You can search the tools by approach, features, discipline and cost to find tools to best support your project. Tools include those to support all steps of systematic reviews and meta-analysis including guidelines, reporting standards, protocol development, search automation, study selection, quality assessment/critical appraisal, extraction and synthesis as well as tools to help with data visualisation and text mining.

Systematic review standards

PRISMA (freely available) 
Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is an evidence-based minimum set of items required for reporting of methodology in systematic reviews and meta-analyses. The PRISMA Checklist and PRIMSA Flow Diagram focus 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, particularly evaluations of interventions.

• The PRISMA Checklist will aid you in ensuring you have followed the correct methodology and reporting of your methods and gives a structure to follow when writing up your review
• The PRISMA Flow Diagram aids reporting by presenting the flow of information through the different phases of a systematic review. It maps out the number of records identified, included and excluded, and the reasons for exclusions

EQUATOR Network (freely available)
More guidance is available on reporting in various types of systematic and research reviews, either focusing on using PRISMA when researching particular subjects such as health inequalities, or when PRISMA is not fully suitable, such as reviews with synthesis without meta-analysis.

Databases of systematic reviews

Searching databases of systematic reviews will be useful if you are doing an umbrella review (a systematic review of systematic reviews) or looking to identify research gaps or ongoing but not yet published reviews. You may find reviews on topics similar to your own, which you can use to inform the planning and methods of your project. 

Cochrane Database of Systematic Reviews (CDSR) (College resource)
CDSR is one of the constituent databases of the Cochrane Library. It contains Cochrane Reviews which are peer-reviewed systematic reviews that have been prepared and supervised by a Cochrane Review Group according to the principles laid out in the Cochrane Handbook of Systematic Reviews of Interventions.

International prospective register of systematic reviews (PROSPERO) (freely available)
PROSPERO is produced by the CRD (Centre for Reviews and Dissemination - University of York). The register is useful for highlighting prospective systematic reviews and enables comparison of reported review findings with the original protocol.

Epistemonikos Collaborative, multi-lingual database of systematic reviews in health. Search results link to the primary studies included in the systematic review, therefore aiming to provide an efficient method of searching.

Limits and filters for systematic review search strategies

Filters are tested search term combinations designed by librarians and researchers. They usually involve a combination of keywords, subject headings and indexing terms and can be added to your search strategy to help identify specific methodologies, study types, populations or subject areas. They work in a similar way to some of the limits provided in databases, but are much more reliable.

Specialised versions of filters have been designed for each database. For instance, the filter to find RCTs in PubMed is slightly different from the filter for RCTs in MEDLINE via Ovid, so you must use a filter that has been designed for each database you are using.

For more on filters:

• the Centre for Reviews and Dissemination ISSG Search Filters Resource lists a wide range of filters
• this helpful guide on filters from Kings College Library has further information on finding and using filters
• ask your librarian for further guidance if you are unsure which filters are right for your search or how to properly integrate them into your searches

Databases, grey literature and trial registers to search

A thorough literature search, particularly for systematic reviews, should include results from a number of databases and could require both published such as journal articles and unpublished (grey) literature including ongoing trials, policy documents, theses and other resources.

Lists of databases, trial registers, and grey literature search engines and tools are available on the Medicine, medical biosciences and healthcare resources page.

A longer, more comprehensive list of grey literature resources is available in Appendix 1 of the Systematic review guide and flowchart (pdf)