If you need help, please contact Hazel Plante, Liaison Librarian at 778.782.4173 or hazel_plante@sfu.ca or Ask a librarian.

Please also see the Services for Graduate Students guide for more general information on what the SFU Library can offer you. See also Evidence-Based Medicine resource guide for background information.

Getting started - PICO

Before diving into database searching, you'll first need to decide which concepts to focus on. When drafting a systematic review, the PICO approach is especially helpful for developing a well-formulated question for your search. PICO stands for:

• Patient or Population
• Intervention
• Comparison (sometimes there is no comparison).
• Outcome

For example, you might be planning a systematic review about supervised injecting facilities. You'll need to specify the exact population (adults?young people? men? women?), what outcome you are looking for, and the comparison intervention, if applicable. Here is an example PICO question:

• in adolescents who inject drugs,
• do supervised injecting facilities
• (compared to using drugs in any other context)
• affect hepatitis C incidence?

PubMed

MEDLINE is the premier database for finding biomedical journal articles. There are different options available to search Medline: Ovid, which offers some powerful advanced search techniques; EBSCO, which has a similar interface to several other databases offered by SFU, and PubMed, from the National Library of Medicine. In addition to the core MEDLINE database, PubMed also includes articles from journals not indexed in MEDLINE, and articles that have just come out and have not yet been added to MEDLINE.

PubMed is available free to anyone online. When accessing PubMed, be sure to connect to it through the SFU Library's website. This will ensure you are able to link to the full text articles that SFUoffers. To access PubMed, first go to Article databases (also available from the Library home page). From here you can search for MEDLINE in the bottom search box or click on the M in the alphabetical listings. When you get to the MEDLINE record, click the last option, PubMed; then click Connect.

When you search PubMed by keyword, an "AND" is assumed between words you type in - i.e., PubMed will search for articles that contain all of the words. After running your search, click "Details" to see how PubMed ran your search behind the scenes:

Here you'll find any MeSHterms - Medical Subject Headings - that PubMed matched with your keywords. PubMed uses a technique called Automatic Term Mapping to match your keywords with relevant MeSHterms. In this example, the keywords supervised injecting facilities mapped to the MeSHterm Needle-Exchange Programs. MeSHterms are official subjects assigned by a human indexer and help you find all articles on a topic, regardless of the specific keywords the author used (supervised injecting facilities, supervised injection, safe injection sites, InSite, etc.)

You can see which MeSH terms have been assigned to a particular article when viewing the abstract; click the plus sign at the bottom of the abstract to see them. (Not all citations in PubMed have MeSHterms; new articles or articles from journals not included in MEDLINE can only be found through keyword searching.) The terms followed by an asterisk are considered the Major Topics (main ideas) of the article.

There is a database of MeSHterms you can use to build your search. To get there, change the drop-down menu next to the search box from "PubMed" to "MeSH" (you'll need to scroll a bit; there are many options). When you search for a term in the MeSH database, you will get a list of suggested MeSHterms. By clicking on a MeSHterm, you can see details and add it to the search box to search PubMed with it:

The definition, or "Scope," of the term lets you know how MeSHindexers are using it. There are also Entry Terms lower on the screen (not pictured here) which redirect to this MeSH - supervised injecting facilities is one such entry term. You can use subheadings to narrow your search to specific aspects of the subject. "Restrict search to major topic headings" will narrow your search to articles in which this MeSH is one of the 3 or 4 terms which are the main idea of the article; this tool is also known as "Focus." "Do Not Explode this term" will search only thisMeSH term and not any more specific, related terms. All three of these techniques might overly narrow your search for purposes of conducting a systematic review; you could miss some good articles.

Always check the details to see how PubMed automatically mapped your search term. Sometimes quite bizarre results come up, or a relevant MeSHterm is missed. For instance, if you search for the keywords needle exchange in PubMed, you will not be mapped to the MeSHterm Needle-Exchange Programs.

Automatic term mapping will not happen if you:

• search for a phrase in quotes ("needle exchange")
• use truncation (using an * to find different word variations: e.g. physio* would find physiotherapy, physiology, physiological, etc.)
• search for a hyphenated term (needle-exchange)
• use a field tag (needle exchange[ti] - this searches for those words only in the title field.)

While automatic term mapping can be helpful, it's best to also explore the MeSH database and the MeSHterms assigned to articles to ensure you're using appropriate search terms.

Limits can help address aspects of the PICO question, such as age or gender of the population. You can also search for specific types of article, such as randomized controlled trials, meta-analyses, or comparative studies. Click the "Limits" link above the PubMed search box to get to this screen:

Clinical queries are an easy way to find systematic reviews, or articles with a specific focus on diagnosis, therapy, etc. The link to the clinical queries search is in the bottom centre of the main PubMed search page, or the bottom of the Advanced Search page. These queries apply complex, pre-built searches called "filters" - also known as "hedges" - to locate systematic reviews or clinical studies.

Search results and finding full text

The default view for PubMed search results is a list of article citations - article title, authors, journal name, volume, date, page numbers. Click any article title to read the abstract (if available), view MeSHterms for the article, and to see the "Where can I get this?" yellow box in the upper right corner:

Clicking "Where can I get this?" will take you to any full text that SFUoffers, or will let you know whether SFU has a copy in print at the Library. If there is no full-text or print copy available, you can order the article using the "Search other libraries/request this item" link.

Search history and saving searches

When conducting a systematic review, it's essential to track the steps you've taken in your search. You can view your search history by clicking the Advanced Search link above the PubMed search box. You can also build complex searches here by combining sets from your search history.

You can save searches in PubMed by signing up for MyNCBI - the link is found in the upper right-hand corner of the PubMed search screen. After creating a personal account, you'll see a "save search" link above the search box. In addition to saving the search, you can create email alerts.

Ovid MEDLINE

Ovid MEDLINE has a clear, step-by-step approach to search building which many people find preferable to PubMed. However, it is a subscription database so not everyone has access to it.

On Ovid Medline's main search screen, there's a box checked which says "Map Term to Subject Heading."This means Ovid will try to match the keyword you type in with a MeSH term, much like Automatic Term Mapping in PubMed does, except out in the open rather than behind the scenes. Start by entering your first concept. For instance:

On the next screen, you get taken to a mapping display which looks like this:

If you click the link for any of these terms, you will go to the "Tree" which shows how it fits in with other MeSH terms; which terms are broader, which are narrower, and how many articles have used this term.

If you check the "Explode" box, Ovid MEDLINE would include in your search any terms included under the term in the tree. For instance, the term Adult has the narrower terms Aged, Middle Aged, and Young Adult underneath it, and Aged, in turn, has Aged, 80 and over and Frail Elderly beneath it. By exploding Adult, you would find articles with any of those MeSHterms. By exploding a term, you will typically find much more relevant articles than if you don't explode. The indexes generally apply the most specific MeSH available, so if an article was about frail elderly, it should have that MeSH applied rather than the broader Adult. PubMed automatically explodes MeSH terms unless you instruct it not to.

Checking the "Focus" box will find articles which have the MeSHterm as one of the 3 or 4 Major Topics of an article. This might narrow your search too much.

"Scope" gives you a definition of the Subject Heading and sometimes notes on related MeSHterms. It will tell you when a MeSH term was introduced. This may be important to know when pursuing your systematic review; as new MeSH terms are introduced each year, they are only applied to newly indexed articles. The scope note will tell you what the previous term was and you can add it into your search if you are considering older literature.

On the next screen, you can choose a subheading to narrow your search results. If you don't specify, all subheadings will be included:

Now you're taken to a screen with search results. PDFor "Where Can I Get This?" icons will take you to full-text articles when available.

To search for multiple concepts, search for each individually and then combine the search sets by using the "Search History" tab at the top of the main search screen.

You can save your search history and create email or RSS alerts by creating a personal account.

Ovid EBMReviews

Ovid EBM Reviews searches 7 databases at once. You can also search these databases individually.

• Cochrane Database of Systematic Reviews - the home of "Cochrane reviews" - lengthy systematic reviews and meta-analyses conducted by expert groups in a standardized way. Protocols for yet-to-be completed reviews are also included.
• Cochrane Central Register of Controlled Trials (CENTRAL) - one of many registers of controlled trials.
• Cochrane Methodology Register - articles about methods used in evidence-based medicine.
• Database of Abstracts of Reviews of Effects (DARE) - critically appraised reviews of the evidence in journal articles; produced at the University of York.
• ACPJournal Club - reviews of journal articles; produced by the American College of Physicians and BMJ.
• Health Technology Assessment - structured abstracts which review health technology.
• NHSEconomic Evaluation Database - articles focused on a cost-benefit analysis of health interventions.

To view the full text of Cochrane reviews, click EBM Topic Review just above the "Where can I get this?" link in the record. (For DARE and ACPJournal Club, click "EBMArticle Review" for full text; for Health Technology Assessment, view the abstract, and at the end, there is typically a link to the original research.)

Cochrane systematic reviews are also indexed in PubMed and Ovid MEDLINE; you can search for "Cochrane Database of Systematic Reviews" as a journal title to limit your search to Cochrane reviews.

With the exception of the Cochrane Central Register of Controlled Trials and the NHSEconomic Evaluation Database, subject headings are not used in the EBMReviews databases; use keyword searching instead.

CINAHL

CINAHL, the Cumulative Index to Nursing and Allied Health Literature, is another database you may want to include in your systematic review search. It has subject headings similar to MeSH, and despite some overlap with MEDLINE, there is much unique content. Use the "Suggest subject terms" checkbox to map your keywords to subject headings:

This takes you to a screen that looks much like Ovid MEDLINE's mapping display, with links to the Tree for subject headings, links to scope notes, and ability to explode or focus.

There are a variety of limits, including age, gender, publication types, date ranges, and more on the bottom half of the main CINAHLsearch screen.

Web of Science

Web of Science is another database for finding health research. It also has some unique features, such as cited reference searching and journal impact factors.

Keyword searching by topic in Web of Science is straightforward. There are subject headings available, called Subject Areas, but they tend to be very generic. There are also "KeywordsPlus" generated from words in the titles of an article's references. You can sort your results by relevance or number of times cited, rather than just by date published. Search results are in citation format, with "Where can I get this?" links to help you find the full article. Click the "search history" link to save your search and create alerts.

Google Scholar

Google Scholar can be another useful source for finding research - particularly grey literature from NGOs or government agencies, which is not indexed in databases like PubMed, Ovid Medline or Web of Science. As with PubMed, be sure to access Google Scholar via the Library's website to ensure you see the "Where can I get this?" links that will take you to full-text SFU offers. Just go to Articles databases under Find on the Library's homepage, then use the Google Scholar box you find there.

Google Scholar searches the full-text of articles, while databases such as PubMed, Ovid Medline and Web of Science search only the title, abstract and subject headings. This means it will often find more articles than the other databases, although some of the articles found might be less relevant if your keywords are only mentioned in passing in the article. Search results in Google Scholar are relevance-ranked rather than sorted by date, so you will likely find very good articles on the first few pages of results; however, they may be dated articles - older, highly-cited articles tend to appear at the top of your search results. You can easily find articles which have cited a paper (although the citation counts are less precise than those you find in Web of Science), and there is also a "related articles" search feature.

There are no subject headings available to use, and a limited search builder feature on the Advanced Search screen. For more complex searches, use parentheses to group your terms, for example:

(supervised OR safe) AND (injection* OR injecting) AND "hepatitis C" AND (adolescent* OR teen)

You may be interested in Google Scholar's advanced search tips, as well as Google's advanced search tips.

There is an option at the bottom of the Google Scholar search screen to create an alert for the current search.

General database search tips

Depending on your specific research topic, there is a host of other databases relevant to health which you might want to search. In particular, TRIP (Turning Research Into Practice) is a rapidly growing evidence-based medicine resource.

Some search techniques are common to most or all databases:

If you're finding too many articles:

• Try adding terms to your search. In some databases, you'll need to type "AND" between the words; in others, such as PubMed and Web of Science, it's assumed.
• Exact phrase searching will also narrow your search.
• Consider using "NOT" to rule out irrelevant articles; e.g. diabetes NOTinsipidus. Use with caution as you may lose some good articles.
• Use any relevant limits - limit to articles published in the last 5 years, limit to review articles, etc.

If you're finding too few articles:

• Think of any possible synonyms you could use and add them to your search by using "OR" between words. Try thinking of broader synonyms; cancer rather than oral cancer, for instance.
• Use both subject headings and relevant keywords, combined with ORs.
• Use truncation (aka wildcard searching) - put an asterisk before the end of a word to find all variant endings. E.g. physio* will find articles using the words physiology, physiological, physiotherapy, etc.
• Check the subject headings - MeSH in MEDLINE, Subject Areas in Web of Science - to get ideas for other ways your idea might be categorized.

Citation Management Tools

Citation or reference management tools collect your journal article, book, or other document citations together in one place, and help you create properly formatted bibliographies in almost any style — in seconds.  Citation management tools help you keep track of your sources while you work and store your references for future use and reuse.