CMA's free MEDLINE service: popular indeed

CMAJ 1998;158:1357

© 1998 Canadian Medical Association

The CMA's OSLER Support Desk is a busy place, with as many as 65 physicians a day calling or emailing about the CMA's free MEDLINE service (see CMAJ 1998;158[6]:799 [full text]). Registrants from every province and territory, as well as several US states, have already signed on. The largest number of OSLER searchers is found in British Columbia, and the most distant participant is in Australia.

Hundreds of doctors have already taken advantage of OSLER's online assistance to formulate their search strategies, save searches and eliminate technical obstacles affecting literature retrieval. Our users range in age from medical school students to cyber-savvy retirees; our oldest participant is an energetic 88-year-old.

Help!

If keywords or subject headings entered during a search do not result in useful references, searchers can send an email SOS by clicking on "Ask a CMA Librarian" on each screen. Search strategies that were tried but failed can be included to indicate how the search was conducted. Often the searcher's problem is a simple spelling error, but the most common difficulty is succumbing to the temptation to string together too many terms in the Keyword box. Remember: OVID software offers ways to apply many limits to a search set. These limits provide the best results when searching is performed in a series of steps.

Refining a search

If conducting a search on glaucoma in children, a natural approach might be to type pediatric glaucoma. So much has been published on this topic searchers are bound to find a few good reviews. However, when those terms are entered during a search of MEDLINE 1995­1998, the system responds with a single article. This is surprising: you know that many more review articles have been published. When displayed, the article indeed includes "pediatric glaucoma" in the title, but the content is of little use.

Try a much more general search. Typing glaucoma and selecting Focus will result in 902 references. This reference-overload problem can be solved by clicking on the Limit icon in the OVID toolbar: it depicts an arrow hitting the bull's-eye on a dartboard. Scroll down the Limits page, select the Age Groups option and apply the limits Preschool child (2 to 5 years) and Child (6 to 12 years). (To make multiple selections, hold down the Control key while clicking on the limits). The result is a much more manageable 93 references. This number can be further reduced by limiting to English language, human and review articles. The final set now consists of 3 citations.

OVID tip: trying out Tools

The OVID interface provides a medley of useful searching aids in the toolbar on the Main Search Page. The Tools icon, a tiny wrench, is essential if you are uncertain about the keyword or subject heading for your topic. When the Tools screen opens, enter your term in the box and choose from the 5 tools listed for information about the term. Users who type glaucoma and select Tree will see an arrangement of subject headings that can help you choose the most specific term possible. The number of articles referenced under each term is also provided, revealing the extent to which your topic is covered. The Permuted Index tool lets you search the huge thesaurus of indexing terms to see if a subject heading exists that contains your term embedded within it. Enter only a single word: typing glaucoma results in 8 related subject headings and the number of articles posted under each. The Scope Note selection defines subject headings and gives suggestions for their most effective use. The Explode function provides the broadest possible number of searchable references for each subject heading. Finally, the Subheadings option lists all subheadings used to further qualify subjects. If you type glaucoma and select Subheadings, a list of 28 qualifiers, such as Complications, Drug Therapy and Surgery, appears. If you select these and click Continue, the resulting search contains articles about glaucoma for which all or some of these subheadings apply.

Refining a broad topic by applying subheadings of interest shortens search time and helps physicians retrieve material that is specific to their interests. The more specific your demands, the more precise and valuable your retrieved articles will be. Even better, you'll avoid the frustration of gathering hundreds of irrelevant references.

CMA members who haven't yet tried OSLER can visit www.cma.ca/osler to register. Email questions should be sent to cmalibrary@sympatico.ca; phone 800 663-7336 x2255 for the OSLER support desk.—Deidre Green, OSLER support librarian, CMA

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