N Evidence-Based Psychiatry - Psychiatry On-line Brazil (3) 10 1998

Evidence-Based Psychiatry:

coordination: Dra Ana C Chaves

Versão em português

Antonio Carlos Lopes*

* Psychiatry Resident, Escola Paulista de Medicina,
Federal University of São Paulo - UNIFESP.

InterNOT MaDLINE!

In the past, MEDLINE could only be assessed at some few local medical libraries, where it had been licensed for use by the National Library of Medicine (NLM). However, in the last few years, MEDLINE has been made available at different Internet sites, at first charged, and more recently on a free basis. One of the most popular sites are NLM's PubMed and Grateful Med pages. They both offer free access to references and abstracts of MEDLINE and other MEDLINE-related databases, as well as charged delivery of full text of articles. They are organized in such a way that you can your search for specific topics, from MeSH terms, to text words, title words, authors' names, publication type, journal name, etc. You can search the whole database range (from 1966 on), or choose specific periods of time (the last five years, for instance). Specific citations can also be tagged, so that you can read their abstracts later on.

Some organizations have also licensed the use of MEDLINE (such as SilverPlatter or Ovid), selling and distributing MEDLINE CD-ROMs, or developing charged Internet pages. Moreover, a growing number of sites now offer access to MEDLINE on Internet, using specific softwares, or just mirrors of NLM's MEDLINE access (see Table 1 and Table 2). Some require  previous registration for use; some are password-protected. There are both charged and free Internet MEDLINE services. Depending on the page, different databases can be assessed. Most sites also offer full text of articles by paying a fee. On the other hand, you should carefully choose a good Internet MEDLINE service, for the same search, performed at different MEDLINE sites, may yield different results. Various MEDLINE search softwares and specific MEDLINE updating frequencies might explain these differences. While some vendors may update MEDLINE records as frequently as once a week, others would have them updated every 6 months or a year (Sikorski & Peters, 1997).

Some other broad or specific databases, like  EMBASE (the European counterpart to MEDLINE), or the Cochrane Library, have their access centralized at some few charged Internet pages (like BMJ, and at the Cochrane Collaboration, respectively).

Spiders, robots, crawlers and mouses

Certainly most of us must have got entangled in the world wide web someday. We usually know exactly what we hope to discover on Internet, but no idea where to find it. From general medical news or guidelines, to patients' self-help organizations home pages, and even somebody's e-mail or home addresses, information on Internet can be yielded quite easily with the help of the called "search engines". They encompass different free sites on Internet, where you can search for specific topics distributed throughout the net, home page addresses, lists of organizations sites, major public interest pages, etc. Different search engines have been devised around the world, yielding different kinds of data. Search engines intercept different new pages on Internet with the help of some programs, termed "spiders", "robots" or "crawlers". These programs explore the whole net periodically, searching for every recently added home pages, links, etc. The frequency of this search varies from site to site. Some, like AltaVista, refresh their databases as soon as every 24 hours. Others remain months without a single new search. Of course, they are neither perfect, nor so comprehensive. Some would only look up new home page names; others do explore the whole text of entire pages, indexing every word found. Some specific search engines have become famous for their scope and wide use, like Yahoo, AltaVista, Hot Bot, Excite, Lycos, Infoseek, etc. (Table 3). What such weird creatures!

Search engines can be classified into two main groups: those with hierarchically organized and those with non-hierarchically organized search methods. In the first group, topics are ranked in a hierarchically decreasing order, from the most widely used terms, to more specific matters. For example, if you want to find where Harvard University's home page is located on the web, a search engine like this would probably first look for a list of universities throughout the world, then find a list of universities in the United States, and finally discover where Harvard University's page is located. All you have to do is to click on the page's address shown, and you will automatically enter Harvard's site. Yahoo and Excite are examples of such search engines. Advantages: they generally yield precise searches, listing only the most relevant sites directly related to your topic of interest. Disadvantages: very specific topics may not be found.

If you want to find very specific subjects on the net, or if you need to list the highest number of pages on Internet where a topic was cited, you had better use a non-hierarchically organized search engine, where every single word, in every page, is indexed. AltaVista is a good example of such an engine. Suppose you are searching for texts related to Capgras syndrome (a rare delusional psychiatric condition) on the web. Probably there will be few (if any) texts available. A non-hierarchically organized search engine might possibly fetch the greatest number of web pages where this syndrome was cited. Furthermore, you can also find some other useful data, like someone's e-mail address. You just have to type somebody's name (sometimes between brackets), and click the "search" button.  Advantages: an extensive search is performed, and the greatest number of sites are yielded. Disadvantages: there may be too much irrelevant  information, with no relationship to your search needs.

If you need to send a letter or an e-mail message to somebody whose address you ignore (for example, the main author of an article), some Internet engines will also help you with this job. BigFoot, WhoWhere and other sites (see Table 4) provide searching for home addresses, e-mail accounts, contact telephone numbers of people or organizations and even road maps (especially those in the USA).

In Brazil, you can find some few search engines with different scopes (Table 5). Cadê?, for instance, is a hierarchically organized search engine quite similar to Yahoo. For more specific searches, you might make use of Bookmarks. Radar UOL also offers extensive searches. It is worth mentioning the good meta-crawler engine called Miner. Meta-crawlers are Internet sites capable of performing a search, at the same time, at different search engines, outputting a result which is the combination of all search engines' results.  Miner provides access not only to international or Brazilian general search engines, but also to some specific medical search engines, software search engines, etc.

Most countries in the world are developing regional coverage search engines. A wide list of search engines, organized according to different countries, is shown in Table 6.

Medical search engines and medical-related sites

Some Internet pages provide these kinds of data. They may comprise medical search engines, or broad medicine related sites. Some are oriented for the clinician, being divided into specialty sections. Others will offer links to major medical associations, on-line medical journals, patients' self-help groups and the like (see Table 7 and Table 8). Radiology imaging databases, CME courses, live Internet broadcasted real-time medical conferences, surgeries videos, etc., are just beginning to be used as new technologies.

Table 1 - Main free MEDLINE access sites available on Internet
                    (MEDLINE Resource Centre, 1998).

Table 2.    Main charged MEDLINE access sites available on Internet
                    (MEDLINE Resource Centre, 1998).

References

Denise Razzouk and Giovanni Torello