Advanced Literature Searching for Higher Degree Students of Nursing

Last update: 28 September 2011,
by Maureen Bell

When you embark on a higher degree the dreaded literature review will loom large in your early preparations. It can seem rather daunting, but if you follow a few simple rules you'll save time, and avoid a lot of confusion and frustration. Essentially you are dealing with two simple components - language, and logic. This page is to help you with both. For printed notes just click here

Language - trawling PubMed for terms and field codes

Logic - constructing your search from the terms you've collected

Useful tips - to save you time

CINAHL - performing the same search on CINAHL

Other databases - moving on from PubMed or CINAHL to Scopus (my favourite) and other sources

Systematic reviews - what they are, and some guidance for those undertaking one

Grey literature - essential searching for a systematic review

Theses - how to find them

Language

One of the problems we all have is that we expect other people to call things by the same name that we do. Even if they don't, in normal conversation this is not a problem, as we rapidly process the alternatives as equivalents. So if I talk about sickness, and you talk about illness it really doesn't matter, as we still understand one another. Databases (with very few exceptions) don't work like this. Instead they search only the exact words we use (including misspellings!). This means that for comprehensive searching you need to provide them with as many possible alternatives as you can. Some of them (like PubMed Embase, and CINAHL) even have their own indexing language, or thesaurus which needs to be considered as well. PubMed has a thesaurus called MeSH - which is simply an acronym for Medical Subject Headings.

I'm starting with PubMed, followed by CINAHL, and the topic I've chosen is - nursing management of fatigue in cancer patients.
Most postgraduate topics will have more components than this, but I'm using a simple example to demonstrate general principles.
At this stage we will just explore the language you'll need to use in your search, without worrying about how many, or how few articles your retrieve, or even how relevant most of them are.

Field Codes

When searching either PubMed or CINAHL it's important to tell the database where to look for words - titles of articles, abstracts, the indexing language of the database. To do this you need to use field codes.

PubMed has a wide range of field codes, but those you're most likely to use are:-

[mh] to search for Mesh terms
eg. neoplasms[mh]

[mh:noexp] if you don't want to explode the search term
eg. neoplasms[mh:noexp] will search only for the term Neoplasms, not those in the list below it

[majr] to restrict your search to major indexing terms only
eg. neoplasms[majr]

[tiab] to search for words in titles and abstracts - this is essential for searching the most recent literature
eg. neoplasm*[tiab]

[tw] Includes all words and numbers in the title, abstract, MeSH terms, MeSH Subheadings, Publication Types, Substance Names, Personal Name as Subject, Corporate Author, Secondary Source, and Other Terms

[ta] to search for (Medline) journal title abbreviations
eg. Oncol Nurs Forum[ta]

CINAHL has a wide range of field codes, but the codes you're most likely to use are:-

TI – Article title

AU – Author

AB - Abstract

MW  - Word in Subject Heading

MH – Exact Subject Heading

- to explode a term in CINAHL you must add a + after the term eg. MH neoplasms+

MM - Exact Major Subject Heading

SO – Publication Name

Method

At first we won't worry about field codes - they'll come later. For a start just use your own words

• Open a Word document and set up a logic grid - you'll need a column for each concept.

A	B	C
cancer	fatigue	nursing

• Perform a simple search, using your own words - cancer AND fatigue AND nursing

• Scroll through the results to see if there are any articles that look as if they're on your topic. What you'll need is one that includes

(PubMed - indexed for MEDLINE)

Very new material will be labelled either

(PubMed - as supplied by publisher)

or
(PubMed - in process)

and will not have indexing (MeSH) terms added to it.

• Once you have found a suitable article click on the title. This will display the article details, plus its abstract, and a link to enable you to view MeSH Terms

• Clicking on the + sign will allow you to see the indexing (MeSH) terms which have been used to describe the content of the article.
  The article I will use here is

Fatigue and physical activity in older patients with cancer: a six-month follow-up study.
Luctkar-Flude M, Groll D, Woodend K, Tranmer J.
Oncol Nurs Forum. 2009 Mar;36(2):194-202.

and the indexing is

Terms with an asterisk after them are Major terms, and represent the most important subject aspects of the article. Those without an asterisk are Minor terms, and represent less important aspects of the article's content. NOTE the asterisk here is NOT a wildcard.

Some of the indexing terms in this example have subheadings - for example /prevention & control.

When searching, using subheadings is very risky, as indexing at this level is rather variable. However prevention & control is an exception to the rule, and is available only as a subheading

• Check it out in MeSH - there's a link to the MeSH Database in the drop down box from the Search box

• Look up fatigue in MeSH
• Scroll down the MeSH page to look at the Entry Terms.

Entry Terms are useful for suggesting to you synonyms or alternative terms that might be used in the abstracts and titles of articles that don't yet have fatigue as a Medical Subject Heading. There's only a single term in this list, but many Entry Terms lists have quite a variety of alternative terms. (See the Entry Terms list below for neoplasms)

• Look up cancer as a MeSH
  You'll find that MeSH uses Neoplasms rather than the term cancer. Under neoplasms you'll see a huge list of more specific subcategories. If you want to search all categories it's very easy, as PubMed's default is to do what's called exploding MeSH terms, and it will search all of the terms in the list of neoplasms - much easier than typing them into your search one by one!

• Scroll down the MeSH page to look at the Entry Terms.

This list of Entry Terms provides suggestions for synonyms or alternative terms that might be used in the abstracts and titles of articles. THis list will provide useful supplementary terms to add to your list.

• Look up nursing as a MeSH. Nursing also has a list of more specific categories which will be searched

• Now udate your logic grid

A	B	C
neoplasms[mh]	fatigue[mh]	nursing[mh]

• Repeat this process with other articles which look relevant to see whether consistent indexing patterns emerge, and to extend your range of MeSH.

• As new material in PubMed is not indexed, and as indexers, being human, are prone to error, or variation in the way they interpret the content of an article, words in titles and abstract need to be searched too.

• Although lists of Entry Terms give you ideas for words to search in titles or abstracts, you will probably think of additional possibilities. Add terms to the logic grid to allow for synonyms and other alternative terms - the list below is not intended to be comprehensive, but will give you an idea of how to build a search. If phrases are to be searched in titles and abstracts, most databases use inverted commas to enclose the phrase, and ensure that words are not searched independently. PubMed does not require this.

A	B	C
neoplasms[mh] neoplasm*[tiab] cancer*[tiab] carcinoma*[tiab] malignan*[tiab] tumour*[tiab] tumor*[tiab] oncolog*[tiab]	fatigue[mh] fatigue*[tiab] exhaustion[tiab] lack of energy[tiab] tiredness[tiab] weakness[tiab] lassitude[tiab]	nursing[mh] nurses[mh] nursing[sh] nurs*[tiab]

Here is what your record of your PubMed strategy should look like.

Logic

When you have finished collecting terms you are ready to search. PubMed requires that Boolean operators are in upper case, so it's important when searching PubMed to use AND, OR, NOT to connect your search terms. PubMed's tutorial gives a clear explanation of how Boolean logic works.

You will need to OR the individual words in each column, and then AND the groups of words together - remembering to use parentheses around the groups of terms from each column to preserve the logic of your search.

This is how the search will appear :-

(neoplasms[mh] OR neoplasm*[tiab] OR cancer*[tiab] OR carcinoma*[tiab] OR malignan*[tiab] OR tumour*[tiab] OR tumor*[tiab] OR oncolog*[tiab])

AND

(fatigue[mh] OR fatigue*[tiab] OR exhaustion[tiab] OR lack of energy[tiab] OR tiredness[tiab] OR weakness[tiab] OR lassitude[tiab])

AND

(nursing[mh] OR nurses[mh] OR nursing[sh] OR nurs*[tiab])

When you have long lists of terms it's much easier to search each column separately, then combine them. When searching each column separately you don't need to use parentheses around the groups of terms.

• Copy and paste the first set of terms into PubMed, and search

• Clear the search box

• Now copy and paste the second set of terms into PubMed, and search

• Clear the search box

• Now copy and paste the third set of terms into PubMed, and search

• Once you have performed the three searches click on the Advanced search option - top right of the PubMed search screen. This will display your search history, and allow you to combine the results - using AND.

Useful Tips

• Open two tabs or browser windows when searching PubMed - this will allow you to have MeSH open in one, and PubMed open in the other. That way it's easy to move between looking up terms and testing searches.

• Look in the Details box (right hand side of the search screen) to see how PubMed has interpreted your search

• Click on the Title of an article to see MeSH terms used to index it

• Use the Entry Terms lists in MeSH to find words to search in titles and abstracts - remember MeSH alone will not produce a comprehensive search

• Expert Searching in PubMed
  This is a single page guide produced by the Countway Library at Harvard University. Don't be put off by the "expert" - it's a very useful and easy to follow guide with lots of examples to help you to take advantage of PubMed's incredible search power.

CINAHL

Unfortunately the same search cannot be simply copied and pasted into another database. Although there may be many similarities field names and abbreviations will be different, and the user interface will sometimes require a slightly different method.

CINAHL also has a thesaurus of indexing terms and called CINAHL Headings, and most of them are identical to the heading used in Medline. CINAHL is constructed in such a way that, unlike PubMed it does not automatically explode terms - you have to instruct it to do so.

If I choose to explode Neoplasms this is how the search would appear

MH neoplasms+

Notice that the field name abbreviation comes before the heading, and the plus sign after it tells it to search all neoplasms.

Below is the logic grid for the same search in CINAHL

A	B	C
MH neoplasms+ TI neoplasm* AB neoplasm* TI cancer* AB cancer* TI carcinoma* AB carcinoma* TI malignan* AB malignan* TI tumor* AB tumor* TI tumour* AB tumour* TI oncolog* AB oncolog*	MH fatigue+ TI fatigue AB fatigue TI exhaustion AB exhaustion TI “lack of energy” AB “lack of energy” TI tiredness AB tiredness TI weakness AB weakness TI lassitude AB lassitude	MW nurs* TI nurs* AB nurs*

You will need to OR the individual words in each column, and then AND the groups of words together - remembering to use parentheses around the groups of terms from each column to preserve the logic of your search.

Here is what your record of your CINAHL strategy should look like

NOTE:-
In CINAHL you need to type your search directly into the search boxes. It doesn't like Word inverted commas around phrases, but recognises only its own style!

This is how the search will appear :-

(MH neoplasms+ OR TI neoplasm* OR AB neoplasm* OR TI cancer* OR AB cancer* OR TI carcinoma* OR AB carcinoma* OR TI malignan* OR AB malignan* OR TI tumor* OR AB tumor* OR TI tumour* OR AB tumour* OR TI oncolog*)

AND

(MH fatigue+ OR TI fatigue OR AB fatigue OR TI exhaustion OR AB exhaustion OR TI “lack of energy” OR AB “lack of energy” OR TI tiredness OR AB tiredness OR TI weakness OR AB weakness OR TI lassitude OR AB lassitude)

AND

(MW nurs* OR TI nurs* OR AB nurs*)

Note: CINAHL gives you an option MW - which will search for that word in any CINAHL Heading

Other databases

There may well be databases, apart from PubMed and CINAHL, that are useful for your topic, and I've included a list of additional databases I think may be relevant for nursing.

The biggest of these is Scopus, and although it doesn't have the sophisticated subject search capability of PubMed or CINAHL it has some extremely useful features which will allow you to extend your search with very little effort. Its greatest strength is its citation searching capacity. You can easily "translate" a PubMed search for Scopus, and while it may produce many of the same articles, there will be lots of additional material, and you will have some extra options available.

To see these additional features:-

• Try copying the title of a really good article from PubMed, and pasting it (enclosed in inverted commas) into the Scopus Search box.

"Predictors of fatigue 30 days after completing anthracycline plus taxane adjuvant chemotherapy for breast cancer"

• Set the in box to Article Title, and search

• Once the result is displayed click on the title of the article

This will allow you to see

• the abstract for the article

• articles which have cited this article,

• the list of references from the bibliography at the end of the article, along with a link to other articles which have cited each reference

Each reference in the list also has links to full text, as well as its own abstract and references.

Systematic Reviews

What is a systematic review?
By Pippa Hemingway and Nic Brereton. 2nd. ed. Hayward Medical Communications, 2009.

Systematic Reviews: CRD's guidance for undertaking reviews in healthcare
Guidelines developed and published by the NHS Centre for Reviews and Dissemination, which can be used as a framework for carrying out systematic reviews or used for information by organisations commissioning reviews.