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Top Tips: Literature Searching

This set of top tips was a collaborative effort between Emily Hopkins (Knowledge Manager at Health Education England, North West) and Amy Finnegan (NLPN and Assistant Information Specialist at NICE). This set of top tips is a brief introduction to literature searching for health information for a more in depth look into searching, take a look at our post on constructing a literature search. There are a number of excellent ways to learn or brush up on your literature skills (e.g. the LIHNN MOOC), so make sure to check those out too!

Types of Searches:

·  Literature Search – a structured, systematic search of the published literature to scope the literature on a given topic, usually within specific parameters (e.g. date range or country of publication). The references retrieved may then be synthesised into a literature review, or form a reading list.

·  Systematic Search (for Systematic Reviews) – this type of search is a much more thorough, systematic search, with the aim of gathering references to everything published that meets the criteria of the question. The search strategy will form part of the write up, in order to be transparent about what literature has been retrieved and to demonstrate that bias has been minimised. The written up systematic review usually critically appraises and synthesises the body of literature, to thoroughly define the available evidence to answer a specific research question.

· Grey Literature Search –This type of search is looking for materials and research produced outside of the traditional commercial or academic publishing and distribution channels, e.g. Government reports, White papers or NHS Frameworks. To find this type of material you will often need search appropriate sites (e.g. or The National Archives) as the vast majority of this literature is not routinely indexed in commercially produced databases. You may need to search some sites directly and on some sites you will be limited to a basic search so it is useful to broaden your keywords, e.g. if the search is focused on Osteoporosis, you might need to search for elderly care.

Search Frameworks:

Below are popular ways of breaking down your search to identify the concepts. You don’t have to use all of the terms to structure a strategy, often you will only need two or three. We have included the most popular examples for the healthcare sector, but there are other variations available.

· PICO:  This breaks your search down into Population/Patient group, Intervention (i.e. treatment), Comparator (e.g. alternative treatment?) and Outcome. This type of strategy is good for reviews of healthcare intervention.

· ECLIPSE: Expectation, Client group, Location, Impact, Professionals, Service. This framework is often used for healthcare management searches.

· SPICE: Setting, Perspective, Intervention, Comparison, Evaluation. You can use this framework when searching for qualitative evidence synthesis

To see how to identify the concepts using a PICO strategy, please look at our blog post on how to develop a literature search.

Types of Databases:

This depends on what topic you are searching, but literature searches are often associated with Librarians in the Health Care sector, so this is what we will focus on.

· Healthcare databases advanced search (HDAS) – If you have an NHS Athens username and password you can access several databases from this resource, including (but not limited to); Medline, Embase, AMED and PsychInfo. This database lets you create one strategy and run it simultaneously across several databases.

· PubMed Advanced Search – This is a useful resource, and open access, but it can be tricky to search.  The advanced search function will let you re-enter (manually) your strategy from Medline, although be aware that you cannot use the adjacency Boolean operator (see below) so lines must be combined using AND.

· Cochrane Library – The Cochrane group produce systematic reviews and protocols. The Wiley Cochrane Library search manager lets you re-create (manually) your Medline search, for example. The database searches across the Cochrane Reviews as well as clinical trials, technology assessments and Economic evaluations.

· Evidence Search – Designed as a basic search, you are limited to a keyword search. However, you can control your search using the filters on the left-hand side. This resource is useful as a one-stop shop for finding high quality health and social care evidence from sources including NICE, Royal Colleges and Government sites.

· Google – Google is not a dirty word and it can be useful, particularly when you have exhausted your database and want to double check that you have captured everything. Use the Advanced search features and the search tools.  We’d recommend reading Karen Blakeman’s excellent blog & gain some tips on how to get the most out of Google.

Boolean Logic:

If you prefer a visual guide, take a look at our more in-depth post on how to develop your strategy.

· AND – A combination term that narrows your search. You are asking the database to only retrieve results that include all of the terms you have included. E.g. Lung AND Cancer

· OR – This expands your search. You are asking the database to retrieve any reference that mentions at least one of your terms E.G. cancer OR carcinoma OR neoplasm

· NOT – An excluding term. You are asking the database to remove certain terms from your results. This one should be used with caution. It is most commonly used to exclude certain trials, e.g. the line: animal/ not human/ is asking for all references that have the MESH term animal but not human. This line is often used in search strategies and is usually followed by NOT’ing the line with the final line of the main strategy so that only results that are human studies are retrieved.

· (Brackets) – Brackets allow you to group certain terms together in one line, you will need to use brackets when you are using more than one word/phrase in a search line. It is often used with adjacency terms. E.g. (cancer adj4 (lung OR breast OR head OR neck)) so this search is asking to bring back all results where Cancer is mentioned within 4 adjectives of at least one of the other terms.

· Truncation* – This is used at the stem of a word to capture all of the possible variations, for instance Cancer could also be cancers or cancerous. By searching for cancer* you are commanding that the search retrieves any results that contains a word that starts with ‘cancer’. But be careful where you place the * as you can end up missing results e.g. if you searched cancerou* you would miss the results on cancer and cancers.  Alternatively, if you place the * too early you can end up retrieving a lot of irrelevant results e.g. canc* would retrieve cancer terms as well as cancellation, cancel or Cancun.

Note: the asterisk is the most widely use way to truncate a word, although some other databases use other symbols; check the help guide if you are unsure.

· Adjacencies – This is similar to phrase searching, but broader. You are asking the database to search for results that you want close together but might be separated by a few words. For instance: Low back pain could be searched as (low adj4 back adj4 pain) – thus it would pick up articles that might list different forms of pain e.g “low back, knee and ankle pain are all treated by surgery X”

· “Phrase searching” – By using double quotation marks, you are commanding the database to return results that contain that exact phrase.


· Limits – Most databases allow you to limit your results in a variety of ways including by date, language and type. Limiting a search by date is the most common limit and often databases will have a drop down box for you to select the date range in which you would like to limit the search. It is best to limit your searches at the end.

· Subject headings – Depending on which database you use, these can be referred to by other names e.g. MESH (Medline) or Emtree (Embase) terms. Subject headings are thesaurus terms that are used to index a record within a database, and are added by database indexers as the way to clearly and concisely define the subject matter, similar to classifications in a library collection.

·  Medical dictionaries – There are several online medical dictionaries, these are good to use to get a quick definition of a condition and to find word variations or synonyms.

·  Search fields – The most common types are .tw (text word), .ti (title) and .ti,ab (title and abstract) – by adding these to the end of a search e.g. (cancer* or carcinoma* or neoplasm*).ti,ab You will retrieve results that are only present in the title and abstract.

·  Capital letters – Surprisingly (and thankfully) these don’t matter!

Useful Resources:

The LIHNN MOOC – A MOOC produced by LIHNN and Michelle Maden. The MOOC has been designed with the input of clinical librarians and covers six key themes that encapsulate literature searching from start to finish.

Reading University: Doing Your Literature Search ­– A Step by step guide on how to create literature review

University of Leeds: Literature Searching Guide – A step by step guide on how to create a literature search, this guide includes templates to help you work through your search.

The University of Manchester: Medicine Subject Websites – This site lists useful health websites aimed at patients and professionals.

The University of York: Health Sciences – Contains a comprehensive list of medical databases that can be used to develop a literature search


One comment on “Top Tips: Literature Searching

  1. Pingback: Constructing a literature search | NLPN

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This entry was posted on November 7, 2016 by in Top Tips and tagged , , .

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