We would emphasise at this stage to consult with a librarian or knowledge specialist before you embark on any searching (link opens in new window). Dependent on your context you are also welcome to contact the Library team at hhsl@uhi.ac.uk to discuss one-to-one meeting(s) to discuss, advise and assist with developing your search strategy . We would expect you to have attempted a literature search in advance, and have a clear idea of your research topic and the specific problems you are having, prior to arranging meeting(s). Depending on your subject area we may refer you to other sources of help/assistance.
While most of the standard medical, healthcare and interdisciplinary databases are appropriate for use in systematic reviews, Pubmed should be used with care. This is due to the fact that Pubmed lacks certain search functionality (for example the ability to code for proximity operators), making it different to search consistently. One of the key characteristics of a systematic review is that everything about it, including the search strategies are reproducible and transparent. Unfortunately due to the complex search algorithms Pubmed employs searches carried out on it are not reproducible and transparent.
Having said this Pubmed does have some useful functionality which is indicated in the useful tools section of this page.
PRISMA-S (link opens in new window) was launched in 2020, outlining all the reporting requirements for literature searching in systematic reviews. Item 8 is: Include the search strategies for each database and information source, copied and pasted exactly as run. Note ‘exactly as run’. This is not possible in PubMed. Medline on the OVID platform (or via EBSCO or other aggregator) is preferred.'
Source: Exploring the Evidence Base (link opens in new window).
There are a large number of databases available to search. These cover the whole gamut of knowledge and are subject specific - for example GEOBase for geography and The ATLA Religions Database for theology matters. For some disciplines systematic reviewing is in its infancy or maybe not the best method to utilise.
For health related systematic reviewing it is recommended that an evidence based approach is taken in which the top level evidence tools are searched first - it is recommended that searching should start with Dynamed, BMJ Best Practice, Campbell Library, Cochrane Library, SIGN, NICE and the EPPI-Centre. If you work with NHS Highland it is also worth using UpToDate - which is only available within the NHS Highland network and the Health Sciences Library PCs.
This is then followed by the databases - which databases you use is determined by your subject - some suggestions are given below. These are not exhaustive and the key to a good systematic review is to use and triangulate as many relevant databases as possible:
If you are attached to a University remember to use databases with broad coverage such as SCONUL and Web of Science. These databases are are multidisciplinary in nature and often can recover materials not covered by the subject specific databases.
Remember also resources which may not seem relevant can be utilised - for example The Philosophers Index can be used by health/social care researchers working on aspects of ethics, and agricultural databases could reveal useful materials on the health related effects of chemical usage or environmental exposure to dust.
Please remember to consider bias in your search strategy and selection of databases. Perhaps the biggest bias in a strategy can be to limit search results to English only. Consider how you would cope with retrieval and interpretation of material published in other languages. Also consider as wide a range of databases as possible. If your review is on educational aspects of health for example make sure you include educational databases as well as health related ones.
Search strategies for systematic reviews are much more complex and thorough than those used in routine searching. You will need to consider the use of:
There are a number of systematic review search strategies framing techniques eg PICO, PECO, ECLIPSE (opens in new window) which can be used to assist to frame your search. As noted a key element of systematic reviewing is that search strategies are reproducible and transparent therefore it is important to fully document your searches. As well as showing someone else what you have done this has additional benefits such as you can quickly copy and modify a search strategy from somewhere else to meet your own needs.
All search strategies should be robust and reproducible and systematic review search strategies are more complex than those you are perhaps used to — they frequently require tens or even hundreds of lines of search terms, a mixture of MeSH and freetext terms, translating search syntax from one database to another, and use of advanced search syntax such as truncation (using * to truncat* words), proximity (using code to search for words being within a certain number of words adjacent to each other), and wildcards (using ? to replace one letter with another).
This guide by the University of Exeter Library (link opens in new window) gives a detailed explanation of how to 'decode' search strategies in systematic reviews.
Another two "decoded" examples are given below
Example 1 - using MESH Headings/Boolean OR/Truncation/Keywords/Synonyms to maximise retrieval of articles around topic of primary care
1. exp Family Practice/ or exp General Practice/ - MESH Headings - exploded and merged using OR
2. exp Physicians, Family/ or exp General Practitioners/ - MESH Headings - exploded and merged using OR
3. general pract:.af. - uses truncation to look for general practice, general practices, general practictioner, general practictioners and uses field search command .af. to look for defined words in all fields of the database. Using .ti. would look for words only in the title field, using .ab. would look for words only in the abstract field.
4. family medicine.af. - as line 3 for keyword
5. exp Family Health/ - as line 1 MESH
6. family health.af. - as line 4 - keyword
7. exp Primary Health Care/ - as line 1 MESH
8. exp comprehensive health care/ - as line 1 MESH
9. (primary care or primary healthcare or primary health care).af. - keyword synonym search on all fields - note terms can be one word or two (primary healthcare or primary health care) cf breast feeding or breastfeeding - also consider alternative spellings - eg organisation organization
10. or/1-9 - Lines 1 to 9 combined together using OR to give a complete set of articles on chosen topic
Example 2 - using MESH Headings/Boolean OR/Boolean AND/Truncation/Keywords/Synonyms to maximise retrieval of articles around topic of health literacy in asthma.
1 exp Asthma/ - MESH heading exploded
2 Asthma*.ti,ab. - asthma truncated - finds asthma, asthmatic, and fields searched .ti,ab. - in the title or the abstract
3 1 or 2 - sets combined using Boolean OR - to give use complete set on asthma
4 exp Health Literacy/ - MESH heading exploded
5 (health* literate or health* literacy or literate health* or literacy health*).ti,ab. - finds elements of synonyms relating to health literacy in title or abstract
6 4 or 5 - sets combined using Boolean OR - to give use complete set on elements of health literacy
7 3 and 6 - asthma and health literacy related sets combined using Boolean AND
These tools will help you improve the quality of your search strategy:
Pubmed ReMiner (link opens in new window): a tool to help you build your search by showing you the most commonly used freetext and MeSH terms used in articles about your topic
Visualizing Pubmed (link opens in new window): provides various formats of data visualisation of the results you find in Pubmed
InterTASC Search Filters Resource (link opens in new window): a collaborative venture to identify, assess and test search filters designed to retrieve research by study design or focus
Library of Search Strategy Resources (link opens in new window): a constantly updated set of resources such as databases, search filters, and tutorials to help systematic reviewers build their search strategies
SIGN methodology filters (link opens in new window): pre-tested search filters designed to narrow results to particular study design types in a range of databases
Database Syntax (link opens in new window): librarian Janneke Staaks has designed a resource which translates search syntax across the most commonly used database platforms
OECD countries search filter (link opens in new window): search terms validated by NICE to limit your search to specific geographic regions
Country URLs (link opens in new window): list of domains to limit search results to websites from specific countries
For any assistance/advice required please contact the Library Team at: hhsl@uhi.ac.uk