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Systematic Review Guide

Overview of the Systematic Review process with links to resources

Searching online best strategies, Boolean and Concept building

AND, OR and NOT

You can use the search operators AND, OR and NOT to combine search terms and concepts. These are the most commonly known and used operators.

The operators AND and NOT limit the number of results from a search. The operator OR does the opposite; it increases the number of results.

Examples:

  • Endangered AND birds : combines these two words
  • Endangered OR birds : searches for the words endangered OR birds. This search will produce more results. (Tip: the operator “OR” can also be used to include different spellings and translations or synonyms in the search).
  • Endangered NOT birds : searches for the word ‘endangered’ and excludes the word ‘birds’.

To see how this works, take a look at The Boolean machine. Move your cursor over the operators AND, OR and NOT to see how they determine your search.

You can also combine more than two search terms. Use brackets to indicate the priority. For example (Money OR inflation) AND banking.

Example of a practical use of 'Concepts' & Synonyms 

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Database search concepts and Boolean:

I want to search for an essay titled: "Discuss the effect of antioxidants on athletic performance"

I can do an 'Advanced Search' this means there will be a number of concept search boxes available with AND between them

Remember the more concepts we combine the fewer and more specific the search results

Within a concept box we can add different variants of similar words (Synonyms) with OR between them to increase the search results

 

Using search aids (Initial simple overview):

Most databases allow you to use * as a trunction symbol; for example Nurs* will search for all words starting with nurs, typically Nurse, Nurses, Nursing

Most databases allow the use of ? as a wildcard, for example Wom?n stands for Women or Woman

Most databases allow phrase searching with the use of inverted commas, eg. "Nutrition support"

Many databases allow proximity searching but the method differs in different databases, eg, In EBSCO  Nutrition N3 Support means that the words need not be in a phrase but need to be within 3 words of each other to be retrieved

Writing a Search Statement: You can use 'Concepts' and Boolean logic to create a Search Statement for your write up, for example a search strategy for the above topic might be:

(Antioxidants or supplements or "nutrition support") AND (Sports performance or athletic performance) 

 

To help with you search strategy 'Do':

  • Contact your Librarian to help with your search strategy, librarians are trained in search strategy!
  • Create a personal login for all databases; this will enable you to save searches and set up search alerts. 
  • Use Subject heading where possible (e.g. Mesh in Medline, PubMed etc) as part of your search strategy
  • Combine the Subject headings search with a Keyword search.
  • For the keyword search cover all reasonable variants of each concept term
  • Use truncation (*) to cover plurals and wildcards (# and ?) to cover variants of a word (eg Colo?r for colour and color)
  • Use proximity / adjacency searching 
  • Explore the 'Help screen' of the database to check the search aids, proximity search, phrase search, wildcard and truncation that works with that database 
  • Citation Checking: If relevant do check the reference list at the end of the article; you can search for relevant journal titles on the main library webpage to check if TUS (Athlone) holds the journal referenced, if not you can request the article as an Inter Library Loan
  • Note: If the journal title is in abbreviated format simply type the abbreviation into a google search with the word ‘journal’ beside it and the full title will appear
  • Citation Chasing
  • Pubmed and ProQuest have  ‘Related citation’ links on their search results to help you find similar articles
  • Google scholar has a ‘Cited by’ and Cited in’ function which can also be used to find similar material.
  • Scopus has a 'Cited by' and related articles link

The Main currently available Science Databases include the EBSCO databases (CINAHL, Academic Search, AMED, SocINDEX); HEALTH RESEARCH Premier; PsycInfo; PsycArticles; Scopus; Wiley Online, Sage, Taylor & Francis, Oxford Journals Collection, JSTOR, Cambridge Journals Online and Science Direct Database; and free databases such as PubMed and Google Scholar. (to be updated as required)

Useful TUS databases for a systematic review include: 

Scopus; Pubmed; Medline (available though EBSCO); Cinahl; Wiley Online, Cochrane Library (freely available) ERIC(freely available) Open Grey (Freely available) Google Scholar and PsychInfo.

Supplementary Materials:  TUS Midlands Research Repository, Lenus, RIAN, EthOS, OpenDOAR, BASE, DART-Europe, SSRN, NICE

Other useful databases include Embase; Web of Science;  ASSIA: Applied Social Sciences Index and Abstracts. Sociological Abstracts, Social Sciences Citation Index,  Age Line, ChildData, Community Wise, Social Care Online, IBSS, IDOX LILACS, PEDro.

 

Useful Tip: Identify Reviews with similar features to your review, on Cochrane, Prosporo and PubMed. This will give insights into possible search strategies and databases. 

LINKS:

Using search aids:

Most databases allow you to use * as a truncation symbol; for example Nurs* will search for all words starting with Nurs, typically Nurse, Nurses, Nursing

Most databases allow the use of ? as a wildcard, for example Wom?n stands for Women or Woman

Most databases allow phrase searching with the use of inverted commas, e.g. "Nutrition support"

Many databases allow proximity searching but the method differs in different databases, e.g, In EBSCO  Nutrition N3 Support means that the words need not be in a phrase but need to be within 3 words of each other to be retrieved. See below for detailed table. 

Review Articles: When reviewing the literature it can be useful to look at review articles; some databases such as PubMed and PsycINFO allow one to use a search limiter for review articles; alternatively the search term 'Review' can be added as an extra search concept

Citation tracking: Also called Citation analysis, or Cited reference searching, is a way of measuring the relative importance or impact or an author, article, or publication, by counting the number of times that author, article, or publication has been cited by other works. Databases such as PubMed; Scopus and Google Scholar have a 'Cited by' link 

Writing a simple search Statement: You can use 'Concepts' and Boolean logic to create a Search Statement for your write-up, for example, a simple search strategy for the essay topic, 'Supplements are a valuable aid to athletic performance, Discuss?',  might be; (Antioxidants or supplements or "nutrition support") AND (Sports performance or athletic performance) 

Note For Systematic Reviews, the Search strategy write-up is more advanced and also needs to be reproducible see tab 'Examples of a Systematic Search Strategy' above.

  • Identify all relevant keywords (independent of any one database) and list them all
  • To help with this: look at similar articles and the keywords assigned also the words in the abstract; think of variants on these key words
  • Identify Relevant MeSH (or other thesaurus terms such as Emtree); to find the relevant MeSH term go to the PubMed MeSH database 
  • Inclusion / Exclusion Criteria may need to be included in your search strategy; dates, language, etc. 
  • Search filters for document type etc may be included in your search strategy.
  • If appropriate the use of extra search features can be helpful; truncation, wildcards, proximity operators etc.  Database 'help link buttons', can provide guidance on what truncation features work in each database
  • Sensitivity versus Specificity: Systematic reviews aim at very high sensitivity with particular search resources
  • Make sure all key papers are included in your search results; revisit the search strategy if this is not the case. 
  • Use references cited in relevant sources to track down earlier works.
  • Identify pivotal early studies if available
  • Search Grey Literature also: Reports, Clinical trials, Specialists sources etc.
  • Document your search strategy, using a notebook or spreadsheet.
  • Create individual logins on all databases and save relevant searches.

Example of a Help screen from EBSCO

Search History

Mesh Terms Used: Translation

When documenting a search strategy it is recommended that a personal account be created in any databases to be searched. The personal account signup option is usually on the upper right. Saved search histories of final searches can then be downloaded from the databases

This is an example of a documented search strategy on Prospero for a rapid review

It is also recommended that a PRISMA  flow diagram of the entire search strategy be included. The PRISMA Flow Diagram Generator  is an Open Source online tool that may assist you in producing your PRISMA flow diagram.

You also need to document your complete search strategy for your own reference: What searches you tried on different databases and what searches worked and were included and what was not included in the final search strategy 

Search Filters – sit on top on your subject searches Carry out your subject searches first, evaluate and make sure you are happy with the relevancy of the results. Then apply the filter.

PubMed search strategy for Systematic Reviews

(((systematic review[ti] OR systematic literature review[ti] OR systematic scoping review[ti] OR 
systematic narrative review[ti] OR systematic qualitative review[ti] OR systematic evidence review[ti] OR 
systematic quantitative review[ti] OR systematic meta-review[ti] OR systematic critical review[ti] OR 
systematic mixed studies review[ti] OR systematic mapping review[ti] OR systematic cochrane review[ti] OR 
systematic search and review[ti] OR systematic integrative review[ti]) NOT comment[pt] NOT (protocol[ti] OR 
protocols[ti])) NOT MEDLINE [subset]) OR (Cochrane Database Syst Rev[ta] AND review[pt]) OR 
systematic review[pt]

Searching Scopus for "Randomised Control Trials" .

 

( INDEXTERMS ( "clinical trials" OR "clinical trials as a topic" OR "randomized controlled trial" OR "Randomized Controlled Trials as Topic" OR "controlled clinical trial" OR "Controlled Clinical Trials" OR "random allocation" OR "Double-Blind Method" OR "Single-Blind Method" OR "Cross-Over Studies" OR "Placebos" OR "multicenter study" OR "double blind procedure" OR "single blind procedure" OR "crossover procedure" OR "clinical trial" OR "controlled study" OR "randomization" OR "placebo" ) ) OR ( TITLE-ABS-KEY ( ( "clinical trials" OR "clinical trials as a topic" OR "randomized controlled trial" OR "Randomized Controlled Trials as Topic" OR "controlled clinical trial" OR "Controlled Clinical Trials as Topic" OR "random allocation" OR "randomly allocated" OR "allocated randomly" OR "Double-Blind Method" OR "Single-Blind Method" OR "Cross-Over Studies" OR "Placebos" OR "cross-over trial" OR "single blind" OR "double blind" OR "factorial design" OR "factorial trial" ) ) ) OR ( TITLE-ABS ( clinical trial* OR trial* OR rct* OR random* OR blind* ) )

This filter was developed by NUS Medical Library (not validated) using MESH and EMTREE terms as Index terms and Keywords.

Useful to search in Scopus for RCTs.

 

Searching Scopus for Qualitative studies

( TITLE-ABS ( ( semi-structured  OR  semistructured  OR  unstructured  OR  structured  OR  informal  OR  in-depth  OR  indepth  OR  face-to-face  OR  guide  OR  guides )  W/3  ( interview*  OR  discussion*  OR  questionnaire* ) ) )  OR  ( TITLE-ABS ( "focus group"  OR  "focus groups"  OR  qualitative  OR  ethnograph*  OR  fieldwork  OR  "field work"  OR  "key informant"  OR  experience*  OR  attitude*  OR  perception*  OR  perspective* ) )

Areas to consider

  • Searching in the overall structure of your review see CRD's guidance for undertaking reviews in healthcare
  • Boolean Searching
  • Search Concepts
  • Searching databases skills: Setting limits - Truncation / Wild-cards - Adjacency / Proximity search - Sensitivity v Specificity
  • Building keywords: Look at good articles / theusarus / reference lists/ Subject searching / other SR's / database subject limiters
  • Proximity Operators*
  • Different databases = different techniques
  • Mesh: Identifying the Mesh term - Free text search v Mesh - explode or focus - sub-terms 
  • Saving searches and alerts
  • Documenting the Search: Pubmed EBSCO etc see examples in the literature
  • SR searching and protocol 
  • PICOs 
  • Inclusion / exclusion: Age / Date/ Language/ Population / Setting / Study type
  • Search Filters
  • Record strategy & Prisma
  • Tips: Are all key papers picked up – look at similar topics for SRs
  • Use and adapt other search strateigies: eg Cochrane / Pubmed has SR filter
  • Clips  other tips on libguide
  • Include Grey Literature

Some examples of Search strategies on Cochrane Library

Exercise Training for Blood Pressure: A Systematic Review and Meta‐analysis

Psychological therapies for people with borderline personality disorder / Search strategy

Psychosocial interventions for self‐harm in adults / Search strategy 

* Proximity operators

Scopus has  two proximity operators:

W/n "within n words of" Example: (manipulat* W/3 (neck OR spine OR spinal)) Any of the terms neck, spine or spinal must occur within 3 words of manipulate, manipulation. ...PRE/n "precedes by" Example: (manipulat* PRE/3 (neck OR spine OR spinal))

Ebsco: N and number eg Hypertension N3 exercise

Proquest: Near/ 3 or Pre/ 3

PubMed: Not applicable