Free MEDLINE (and free help) for CMA members!
CMAJ 1998;158:799
© 1998 Canadian Medical Association
Last September 200 CMA members joined the OSLER (Ovid Search: Link to Electronic Resources) trial, and for several months they searched the MEDLINE, AIDSLINE, CancerLIT and HealthSTAR databases via the Internet. Since then participants have indicated that this free and unlimited access to these services is an increasingly important part of their clinical and research work. By the trial's end in December, 94% of the group was searching MEDLINE from 2 to 4 times per week.
OSLER is now available to all CMA members at www.cma.ca/osler. Free searching of MEDLINE databases and OSLER searching manuals, as well as online help with search strategies, are already being used extensively by members. The online assistance is provided by an experienced medical librarian in the CMA library in Ottawa; members may forward email requesting search assistance from every screen. Future plans for OSLER include training sessions for the many physicians who have requested them.
MEDLINE's scope
MEDLINE offers searchers close to 9 million bibliographic references in databases that first became available to physicians in 1966. Most doctors have relied on medical librarians to conduct comprehensive literature searches, especially since MEDLINE, until recently, required command language and a dial-up process that most physicians found intimidating. Today easy Internet access and intuitive software have made exploring the system relatively easy, even for neophytes.
How is MEDLINE able to provide more relevant answers to medical questions than search engines like Yahoo or Alta Vista? These engines look for a string of keywords and produce a list of Web sites that contain some or all of them. MEDLINE limits its searches to articles from authoritative journals and allows users to tailor results with fine accuracy. The capability of a Web search engine to home in on a topic is limited, so the final results will contain many "wrong hits."
Searching MEDLINE with the OVID interface through the CMA offers many ways to customize a search. Once a keyword has been entered on the opening screen, Ovid leads the user to a list of subject headings used by indexers at the National Library of Medicine, where MEDLINE is maintained. Using these medical subject headings, known as MeSH terms, ensures that a search is comprehensive.
Performing a subject search
To find articles about Guillain-Barré syndrome, type the words into the textbox on the Main Search Page and click Perform Search. Ovid immediately presents a screen that names polyradiculoneuritis as the MeSH heading for this subject and lists the number of articles available. Click the tick-box beside polyradiculoneuritis to choose the heading and click Continue, and a list of subheadings appears that can be used to refine the search. To gather the largest possible set of articles, choose to include all subheadings. After reviewing the retrieved references, attach limits (such as English language) to the set to reduce it further. To apply additional limits, click on the Limit icon in the toolbar.
To link Guillain-Barré syndrome with another specific condition or therapy, combine the 2 concepts in a single line. For example, type polyradiculoneuritis and facial paralysis into the text box to retrieve references in which both terms have been indexed. Another approach is to perform separate searches for several concepts, then link them by using the Combine icon from the toolbar.
At times a quick search for a keyword or textword without using a MeSH heading is appropriate. A herbal remedy promoted in the popular press may not yet have a MeSH heading. Type in St. John's wort, for example, click off the "Map to Subject Heading" box, and hit Perform Search. Articles that are retrieved will contain the precise words St. John's wort in the title or abstract.
Searching MEDLINE can be very satisfying, especially when you have ready access at work. It takes a little time to learn the many ways to ferret out articles, but every session leads to more successful results.
If you have questions about search strategy or how to print, save or email your literature searches, simply click on the Ask a CMA Librarian link to send email, or telephone 1-800-663-7336 x2255. Future articles will answer some questions from OSLER users, discuss how to search by author and journal name, and explain the use of the Focus and Explode functions.
— Deidre Green, OSLER support librarian, cmalibrary@sympatico.ca.
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