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Advanced literature search and systematic reviews

An introduction to systematic reviews

Perform your search

The literature search for a systematic review is a long process. Before you start, you need to ensure that the question you are researching is viable. Make sure that: 

  • Your research question has been validated by your supervisor.
  • You have done a scoping search to confirm that there are no systematic reviews (either finished or in progress) covering your question, and there are enough studies available on your chosen topic. 
  • You have identified the relevant search terms for your question.

This section will cover how to create a search strategy, and which techniques you can apply to improve your search.

Planning a search: The basics

You cannot type your research question in a database search box, and expect to retrieve relevant sources. You need to identify the main concepts of your question, and the key terms you can use to research your topic. Your search terms determine the range of results you will retrieve from each database. Using a framework, such as PICO (see Step 1), can help you. 

For the question, Are mind body therapies a viable alternative to prescription drugs to control headaches in children? the main concepts are: children - mind body therapies - prescription drugs - headaches.

Using AND / OR

By combining these terms using the operator AND, you will retrieve results where all the 4 concepts are covered:

Children AND mind body therapies AND prescription drugs AND headaches

Combining your search terms using ANDHeadachesMentions Children AND Mind body therapies AND Headaches AND Prescription drugs

Subject heading and keyword searching

If you are studying any of the health science disciplines, you should use Medical Subject Headings (MeSH) or subject headings.

A MeSH search is very effective and helps researchers find more refined and relevant results than those retrieved through a keyword search.

When you do a MeSH search, you can only enter one search term at a time.

MeSH tools are available on selected databases, such as Medline complete, Embase and Amed.

A keyword search is performed as a backup to the MeSH search. The MeSH subject heading may not exist in the database you are using. 

A keyword search (or free text search) is not as precise as a MeSH search, and it may retrieve some irrelevant results. It retrieves studies where the keywords you have entered appear somewhere within the study, rather than retrieving papers that focus on those terms.  

Supplementing your database searches

After you have performed your database searches there are a number of ways you can supplement your search to retrieve studies you may have missed.

You can browse the contents of key journals to find studies you may have missed via Browzine.

This is used to explore the impact that a source has had on research in a specific field. You can find out who has cited your source and in which journal, and how many times the paper has been cited since its publication. 

You should also browse the reference lists of the papers you have retrieved using your keywords or subject heading (MeSH) search. 

Citation and reference tracking using SCOPUS

Citation and reference tracking using Web of Science

To supplement your database search you should search online open access repositories and gateways. 

Repositories are archives for collecting and disseminating digital copies of the research output of an institution or organisation. 

Gateways are resources where researchers share their research online.

You could contact the authors of key studies you have identified to find out more about their research. Their contact details are usually on the articles you have retrieved. You could check their website for a list of recent and forthcoming publications. 

Look at social networking sites (e.g. ResearchGate and or support networks (e.g. CHAIN online support network for people working in health and social care).

Keeping your search up to date

Whilst you are screening and analysing your results, more articles relevant to your search may be published. You can ensure you are made aware of these using the following tools:

Alert Services

Database alerts

Most databases allow you to set up search alerts relating to a search you have performed.

Whenever a new article appears in the database, which contains your search terms, details of the article will be sent to you.

Some databases also allow you to set up citation alerts which allow you to know when a key study relating to your research is cited. Some also allow you to set up author alerts which inform you when work by a particular author is cited.

Journal Content alerts

You can create alerts so that the latest contents of selected journals are sent to you when they are published.