Searching the literature
There are many reasons to search the literature — keeping up with the latest developments in primary health care (PHC), informing policy and practice, finding out what has already been done in an area, learning something new… With a wealth of information available, how do you efficiently find the most appropriate literature to answer your questions? This Guide provides tips on literature sources, search strategies, limits and filters. Click on the flip cards displayed to follow our example throughout the Guide.
Why do I need this information?
The first step is to identify the reason for searching the literature as the purpose and context will influence where to look and what terms to search for…
I need to know…
Are there any reviews of programs targeting multimorbidity? I need to write a policy brief
What are my search terms?
Searching any source for literature will require careful selection of keywords that adequately address the concept you are interested in. Remember to choose your terms carefully. Hersh and Kickman (1998) suggest that successful simple searches contain only two to three main concepts/keywords.
- Consider synonyms when selecting keywords – there may be inconsistent use of terms across sources (e.g. knowledge exchange, knowledge translation, knowledge mobilisation)
- Consider plurals (e.g. child or children)
- Consider spelling variations (e.g. behavior and behaviour)
Developing a clearly defined research question will help with identifying specific keywords of interest. These will be the terms (also known as textwords) that are entered into a simple search on any web trawler or academic database.
Many bibliographic databases will have their own guides for searching. However, here are a few tips that can be applied across a range of sources.
My keywords and concepts are…
My search terms will include…
Programs AND Multimorbidity AND Review;
Program? (to capture programs, programme, programmes);
?morbidity (to capture comorbidity and multimorbidity)
Tricks of the trade
Where should I look?
There is a wide range of literature sources available. PHC is a broad field thus relevant literature may be found in both specific (e.g. Australian Journal of Primary Health) and broad journals (e.g. BMJ), in addition to ‘grey’ literature sources (e.g. government reports). Identifying appropriate sources to search will stem from the reason for the search.
It is important to identify what types of evidence you are looking for i.e., books, research reports, systematic reviews, case studies, clinical guidelines (Sladek, 2008). The availability of different levels of evidence (i.e., high level evidence may include systematic reviews or randomised controlled trials) will depend on the particular concept of interest. (See Getting Started Guides on Rapid responses and/or Different research Designs)
I will look in…
- Government documents via the Department of Health Website or Google (with .gov added to my search terms)
- Conference proceedings
The next step may be a simple search through the web (e.g. Google) if seeking general information/basic definitions. When reading material in links sourced by these search sites it is important to be cognisant of the credibility of sites; those which include ‘.gov’ in the URL may be more reliable sources than other examples.
In order to do a preliminary scope of the available academic literature Google Scholar may be a useful place to start. Typing simple textwords into a search can provide an illustration of the breadth of material that is available.
Traditionally literature searches will require searching bibliographic databases which contain thousands of references from hundreds of different academic journals. Some of these databases are free and publicly available, while others will require institutional membership. Academic databases are often themed, that is they may focus on a particular area of interest (e.g. Ovid’s Medline specialises in biomedical literature while CINAHL focuses on literature of relevance to nursing and allied health), a particular type of research (e.g. the Cochrane Database of Systematic Reviews) or the journals of a particular publisher (e.g. Wiley or ScienceDirect).
Depending on the concept in question, it might also be necessary to access the grey literature (i.e., non-peer reviewed journal publications such as reports or data sources).
Note: MEDLINE is a subset of PubMed, the advantage of MEDLINE is that a controlled vocabulary, ‘Medical Subject headings (MeSH)’ can be used. However, until MeSH terms have been added to a publication it will not be captured using MEDLINE, for this reason PubMed is often preferred when the latest publications (pre-print and in-process) are sought.
When do I set limits?
The amount of literature available can be overwhelming and as time-poor researchers, practitioners and policy makers, it can be difficult to know how to sort through it all.
Sometimes it is necessary to build boundaries around searches. Examples include limits on:
- Time period (e.g. literature from the past 5 years or 12 months)
- Country of origin (e.g. Australia only)
- Peer-review status (e.g. only include peer-reviewed literature)
- Accessibility (e.g. free full text)
- Language (e.g. only English)
- Type (e.g. only reviews).
I will limit my search to…
- English language
- Published in the last 5 years
Some sites offer the possibility of limiting the fields in which searches are conducted; for example, looking only for keywords that exist in the title of a paper or the title and abstract from a particular reference. In Google Scholar the advanced search option allows the searcher to specify where the keywords need to be found. In PubMed adding the field tag [tiab] in the search box will limit searches to title and abstract only, while [au] will enable a search of only author names.
Search filters have been introduced to make it easier to access a particular body of information. Optimally these are experimentally-created, evidence-based, standardised, systematic, subject-based search strategies (Brown et al., 2014). The filter does the hard work for you by determining synonyms of the key concepts using a validated method, and creating a search string which pulls relevant literature from within the database. It must be noted however that this is best used as a scoping tool in the initial stages of a search.
There are many filters available depending on the topic of interest. For example:
- CareSearch for palliative care
- LIt.search for Aboriginal and Torres Strait Islander health literature
- Health Evidence (formerly health-evidence.ca) offer a systematic review search filter (Lee et al., 2012)
- PHCRIS hosts the PHC Search Filter, a tool which provides access to the broad PHC literature within the PubMed database with one easy click
- Collections of search filters
- Flinders University, Australia
- ISSG (InterTASC Information Specialists' Sub-Group) curate a list of search filters grouped by study design or focus.
Some databases have created their own filtering approach by introducing subject headings or their own thesaurus. For example, all articles in Medline are indexed using MeSH terms (Medical Subject Headings) which enable subject-based searches (Sladek, 2008).
Critical appraisal of search filters is important to determine the sensitivity, specificity and validation of the filter. Look for filters where this has been reported, or to appraise a filter visit the ISSG website.
- Once a particular paper has been located, it is often useful to source the full text of the document. Access to, and availability of, the full text will depend on the stipulations of the database, the institution and the publisher.
- When key papers are identified, a snowballing technique can be used to gain access to additional literature. Most journal article web pages will include ‘similar to’ and/or ‘cited by’ links; these pages will indicate who else found this paper valuable and highlight other works that might be of relevance; it is also useful to scan the reference list of the key papers.
- It is beneficial to save copies of citations and/or pdfs of the full text articles and there are citation management packages available which allow direct export from journal sites. Platforms such as EndNote are commonly used in academic circles as they can be used to a) import bibliographic information directly from databases into the programme, and b) export the citation and a reference list into a working document.
- Making use of the literature retrieved will depend on the aim of the search. However, it is often valuable to critically appraise the literature before applying its findings in your work.
My next steps are to…
- Save references to my citation manager
- Snowball search from my favourite articles
- Critically appraise the material
Resources and references
- Brown L, Carne A, Bywood P, McIntyre E, Damarell R, Lawrence M, Tieman J. (2014). Facilitating access to evidence: Primary Health Care Search Filter. Health Information & Libraries Journal, 31(4), 293–302.
- Hersh WR, Hickam DH. (1998). How well do physicians use electronic information retrieval systems? A framework for investigation and systematic review. JAMA, 280(15), 1347–1352.
- Lee E, Dobbins M, DeCorby K, McRae L, Tirilis D, Husson H. (2012). An optimal search filter for retrieving systematic reviews and meta-analyses. BMC Medical Research Methodology, 12, 51.
- Sladek RM. (2008). Guide to searching effectively in palliative care. CareSearch Information Sheet No. 3. Adelaide: Flinders University. [PDF 307KB]
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Primary Health Care Research & Information Service (2017). Getting Started Guide: Searching the literature. From phcris.org.au/guides/searching_literature.php (Accessed 13 Dec 2017)