To illustrate how easy it is to convert ELHILL commands into PubMed commands, this article will transform a Technical Bulletin Gold Standard search strategy into a PubMed search strategy. Two of the biggest syntax hurdles will be to break the habit of using parentheses rather than square brackets to qualify search terms, e.g., [pt] not (pt), and to remember that Boolean connectors must be entered in uppercase, e.g., AND, OR, and NOT. The search "The client is a layperson who wants information on alternative treatments for breast cancer" was taken from the January-February 1997 issue. Figure 1 is the ELHILL search strategy originally formulated for CANCERLIT which explains search statements 9-11.
The PubMed Boolean Search page was used to recreate the ELHILL search strategy, in Figure 1, into a PubMed search. The Boolean Search page is best suited for constructing complex (or lengthy) search strategies-the query box is larger and scrollable which allows you to view your search strategy in full. To get there, click on Advanced Search from PubMed's Homepage and then click on the Boolean Search link.
SS 1: exp *breast neoplasms
SS 2: exp *alternative medicine
SS 3: 1 and 2
SS 4: *holistic health or *wit a#d humor or exp *psychotherapy
SS 5: 1 and 4
SS 6: exp *breast neoplasms/dh
SS 7: 3 or 5 or 6
SS 8: 7 contains eng (la) and 7 contains human (mh)
SS 9: 8 and 96 (yr) or 8 and 95 (yr) or 8 and 94 (yr)
SS 10: 8 and 93 (yr) or 8 and 92 (yr) or 8 and 91 (yr)
SS 11: 9 or 10
Before you continue reading, at this point if you are still not familiar with PubMed, it is recommended that you review the listing of PubMed's search rules and syntax on Page 12. Otherwise, the translation detailed below from ELHILL language to PubMed may not be as clear.
The query box on the Boolean Search page must contain the entire search strategy as a single search statement as illustrated in Figure 2.
alternative medicine [majr] OR holistic health [majr] OR wit and humor [majr] OR psychotherapy [majr] AND breast neoplasms [majr] OR breast neoplasms/diet therapy [majr] AND english [la] AND human [mh] AND 1991:1996 [dp]
The first step in converting the ELHILL search strategy into a single search statement for PubMed was to create the three search statements that would be OR'd together (i.e., 3 or 5 or 6). Each of those search statements converted into a PubMed search statement follows:
SS 3: breast neoplasms [majr] AND alternative medicine [majr]
SS 5: holistic health [majr] OR wit and humor [majr] OR psychotherapy [majr] AND breast neoplasms [majr]
SS 6: breast neoplasms/diet therapy [majr]
Note: PubMed automatically explodes MeSH terms, whereas on ELHILL you must specify whether or not a term is to be exploded (e.g., breast neoplasms [majr] is equivalent to exp *breast neoplasms). The ability to turn off an automatic explode will be available soon. So, keep in mind that the same syntax is used for terms that are explodable as well as for terms that do not have any indentions. For example, the MeSH terms, "Holistic Health" and "Wit and Humor" (neither have indentions) are entered as holistic health [majr] and wit and humor [majr] and the explodable MeSH term "Psychotherapy" is entered as psychotherapy [majr].
Boolean search statements are processed left to right. To change the order in which PubMed processes a search statement, enclose the individual concept in parentheses. The terms inside a set of parentheses are processed as a unit and then incorporated into the overall strategy. Below are two examples of how the above PubMed search statements can be OR'd together with or without parentheses:
Example #1: breast neoplasms [majr] AND alternative medicine [majr] OR (holistic health [majr] OR wit and humor [majr] OR psychotherapy [majr] AND breast neoplasms [majr]) OR breast neoplasms/diet therapy [majr]
Example #2: alternative medicine [majr] OR holistic health [majr] OR wit and humor [majr] OR psychotherapy [majr] AND breast neoplasms [majr] OR breast neoplasms/diet therapy [majr] PubMed can handle large explosions for over 9 million citations in a blink of an eye. While you should apply logic in formulating a search, all those lessons about segmenting your terms into separate search statements for computer and cost-efficiency are just not vital to the new PubMed technology. That said, however, PubMed includes a "detail" button where you are able to view a picture of the strategy-similar to Internet Grateful Med's "Details of Search" button. Here we will provide clarifying messages such as terms that have no postings. In addition, this feature includes an edit function so that a search strategy can be easily revised and resubmitted; and intermediate postings shown.
The remaining portion of the search strategy is to apply the search limiters for language (i.e., english), study group (i.e., human), and a date range (i.e., articles published during 1991-1996). Whereas, on ELHILL to apply the desired limits in CANCERLIT took an additional four steps (i.e., ELHILL search statements 8-11), this can be easily translated on PubMed into the syntax below and then added (ANDed) to the search strategy.
english [la] AND human [mh] AND 1991:1996 [dp]
To ensure that the ELHILL search strategy was correctly converted to PubMed, the search strategies were run in their respective systems to compare search results. The ELHILL search was run in MEDLINE, MED93, and MED90. In both ELHILL and PubMed, the results were the same - 37 was the total postings.
If you have any questions or comments about the PubMed search strategy, please contact PubMed customer support by clicking on the "Help Desk" link.
Helpful Hint:
While constructing a complex (or lengthy) search strategy for PubMed, it is helpful to use your word processing software as a scratch pad. Use the word processing software to enter your search terms, the correct syntax (e.g., search field tags enclosed in square brackets, Boolean connectors in all uppercase), and spell check. It helps to use extra spaces or blank lines to separate your concepts for ease of proofreading and checking your logic. Once you are satisfied with the search strategy, "copy and paste" it into the PubMed query box. Be sure to remove all extra spaces, hard carriage returns or other special word processing codes. You can then go back to the search strategy in your word processing software to edit or reformulate the search strategy-quickly and easily. Repeating the "copy and paste" step into the PubMed query box will then let you execute the revised strategy with just a few clicks.