Features - Update to Researching Medical Literature on the Web

Gloria Miccioli has been a law librarian for 20 years. Her specialty is research.  She has worked as Government Documents/Reference Librarian at the Jacob Burns Law Library of the George Washington University Law School; as Senior Research Librarian for Williams & Connolly; and is currently International Librarian for Jones, Day, Reavis & Pogue's  D.C. office, where she provides expert research services for the firm's overseas offices.

Editor's note:  This article is an update to Researching Medical Literature on the Web (published June 1, 1998).  There are additions and changes to some Web site addresses as well as new content.  All updates are indicated by        (yellow background color) for easy identification.


        Introduction

After preparing this article, I have become convinced that there are at least as many medical Web sites as there are legal ones, which is good news for the researcher with a small to non-existent medical collection. The Internet provides free access to a great deal of the medical literature, either in full text or citation/abstract format, and it offers search capabilities good enough to fulfill most information needs.  In addition, public demand for medical information on the World Wide Web is strong and growing. Many professionally oriented health care sites are evolving to meet consumer needs, and consumer-oriented sites often include professional literature.1

Journals, dictionaries, textbooks, indexes - all can be found on the Net in growing numbers. The sources are varied: publishers, government agencies, professional organizations, and health libraries, to name a few. A simple, if time-consuming, way to find lots of health-related links is to access the Yahoo! search engine and select the category, "Science."  Click on "Medicine" and you will pull up almost 100 subcategories, including "Libraries," "Journals," and "Dictionaries." Each subcategory links to various sites, of which some may be useful - or not. Under "Dictionaries" are links to seven medical dictionaries, including one with terms in several European languages. You can also search by subject in an attempt to narrow the number of hits and get the mixed bag that usually results from a Web search on a general search engine.

Medline

A more specific approach would be to directly access a medical Web site. But which one?2   As usual, it depends on what you're looking for. MEDLINE, one of the jewels of medical research, is an electronic index that provides citations/abstracts to some 3900 American and foreign biomedical journals since 1966. As such, it is a mainstay of medical research, especially for current information. It has long been searchable for a fee through commercial databases. It is now available on the World Wide Web. Since it is produced by the National Library of Medicine, a government agency, it is offered at no cost on the Net and is accessible not only from the NLM web site but also from many other sites, such as those of medical libraries, medical associations, and other health-oriented sites.

A list of Web sites where MEDLINE can be searched for free is found at Dr. Felix's Free MEDLINE Page. Dr. Felix provides a handy chart that lists MEDLINE sites with links, plus any registration requirements, usage restrictions, document delivery options, and links to additional information. It even lists International MEDLINE Links for MEDLINE information in foreign languages.  It is important to note that not all MEDLINE sites are the same. As Dr. Felix says, "...some of these sites only provide free access to certain parts of the vast MEDLINE database. Some permit quite detailed searching, others simple keywords only. Some have usage restrictions..." In fact, MEDLINE is available from the National Library of Medicine in two official versions, Pub Med and Internet Grateful Med. The two Web products are both similar and different.

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Internet Grateful Med

Internet Grateful Med (IGM), offers assisted searching of MEDLINE and 14 other databases.3  Each database must be searched separately.  The files are:

  • PREMEDLINE: Introduced in 1986, it provides basic citations/abstracts before the data is put into MEDLINE. It is updated each weekday with no subject headings or guarantee of quality control. Once the record is added to MEDLINE, it is deleted from PREMEDLINE. PREMEDLINE is free only through IGM or PubMed.
  • SDILINE: Selective Dissemination of Information online; covers cites from the most recent complete month in MEDLINE.
  • OLDMEDLINE: Covers articles from 1964-65; cites only.
  • MEDLINE: Cites and /or abstracts from 1966-.
  • AIDSLINE: AIDS and related topics, 1980 and after.
  • AIDSDRUGS: Directory of substances being tested in AIDS-related clinical trials.
  • AIDSTRIALS: Clinical trials of substances being used against AIDS and HIV.
  • HealthSTAR: Information on health administration.
  • DIRLINE: Directory of information sources.
  • HISTLINE: Information on the history of medicine.
  • HSRPROJ: Health services research projects in progress.
  • ETHICSLINE: Ethics and related public policy issues in health care and biomedical research.
  • CHEM ID: Dictionary of chemicals, updated quarterly.
  • POPLINE: Family planning, population law and policy.
  • SPACELINE: Space life sciences; MEDLINE cites plus cites from NASA (1961-).
  • TOXLINE: Toxicological, pharmacological, biochemical, and physiological effects of drugs and other chemicals.

Internet Grateful Med was designed for the end user; knowledge of a search command language is not necessary. In addition, Grateful Med helps the user find precise medical terminology, i.e., MeSH headings. The National Library of Medicine has developed an extensive controlled vocabulary called Medical Subject Headings (MeSH); using MeSH terms in a search will lead to greater accuracy and relevancy in search results. By entering a term in Grateful Med and then clicking on "Find MeSH/Meta Terms," you can access NLM's Unified Medical Language System's Metathesaurus. Just browse through a ranked list of terms, MeSH hierarchies, and relevant co-terms, then select terms to be added to your search. You can also designate MeSH headings to be "major topics."Terms will also be automatically "exploded"; that is, subheadings of a term will be searched along with the main heading.

The IGM search screen allows users to also search by keyword, author or title words. Limiting by language, age group, study group, date range, publication type, gender, and journal title (searching from one to fifteen journal titles at a time) is possible via pull-down menus. Records can be viewed or downloaded in citation or abstract format. The full-text can be ordered online for a fee from the NLM Loansome Doc delivery system.

Internet Grateful Med strikes me as a good Web product. NLM has put a great deal of effort into making it user-friendly. While searching is not as powerful as MEDLINE on Dialog, it comes close. Having the system present you with relevant MeSH headings allows for better searching than using only key or title words and is very convenient for the searcher who is unfamiliar with medical terminology. The Metathesaurus function itself is somewhat confusing at first. I recommend reading the The New User's Survival Guide and doing a few practice searches.

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PubMed

PubMed is both broader and narrower in scope than Internet Grateful Med. PubMed was developed by the National Center for Biotechnology Information (NCBI) at the National Library of Medicine in conjunction with publishers of medical literature. PubMed not only indexes articles but also links to the full text of journals at the Web sites of participating journals. At present there are links to the full text of about 100 journals (out of some 3,900 indexed by MEDLINE). Access to the full text depends on the publisher; some require a fee or subscription. You can check a list of titles at http://www.ncbi.nlm.nih.gov/PubMed/fulltext.html. Unlike IGM, which accesses 14 databases besides MEDLINE, PubMed covers only MEDLINE and PREMEDLINE, plus links to NCBI's molecular biology databases. However, for a participating journal indexed selectively for MEDLINE, PubMed includes all articles from that journal, even if MEDLINE does not.

PubMed seems to be aimed at the more experienced searcher or health-care worker. Like many Web-based search engines, PubMed offers Basic and Advanced searching. The Basic screen allows keyword searching by terms, author names, journal titles and date ranges. The Advanced search mode is much more sophisticated. ( Note: NLM has announced that the Advanced Search Page will be revised, but most of the following features will remain.) With the Advanced Search Page, you can use pull-down menu field selection or a PubMed command language to build and modify a search strategy. Fields include author name and affiliation, journal title, issue, volume, publication date, language, text word, title word, substance name, and MeSH headings ( headings can be designated "major")4, and all fields. The Boolean operators AND, OR, and NOT can also be used. For a complex search, I would choose PubMed over Internet Grateful Med.

Both IMG and PubMed use the PubMed search engine, which automatically tries to match search terms, phrases, author names, and journal titles against established lists. Putting a phrase in quotes will prompt the system to search a second phrase dictionary. If a match is not found, the individual terms are ANDed together. It is also possible to search the MeSH headings in both IGM and PubMed.

In PubMed, for either a basic or an advanced search, you can click on "MeSH Browser"; enter a term and MedPub will respond with the correct MeSH heading(s), which can then be selected. When I entered "norplant", I got the MeSH heading "levonorgestrel" and a short definition. You can also view the term hierarchy, from which you can select more terms to add to your search. Or, on the Advanced screen, you can enter a term into the query box, select a field from the pull-down menu, and then select a search mode. "Automatic" searching instructs PubMed to automatically search for the terms that have been entered in the field that has been selected. "List Terms" mode displays an alphabetical list of available terms for the selected field; you can choose terms from this list to add to your search. This list is also useful if you can't spell the term!

Search results in PubMed and IGM are first displayed in brief citation format. Abstracts, if available, can be selected. One of the most useful features is the ability to retrieve related articles for most citations. Most records in MEDLINE are linked to other records by a matching algorithm. This is like the "More" feature in Lexis/Nexis. For the full text of the articles, you can link to a participating journal or order online from NLM through Loansome Doc. In PubMed, there is also a link to the articles of participating publishers.

PubMed has several other useful features.  The Journal Browser lets you look up journal names, MEDLINE abbreviations, or ISSN numbers.  The Citation Matcher allows you to verify article citations.  A Clinical Query Form is available to search for the therapy, diagnosis, etiology and prognosis of a topic. 

I like Internet Grateful Med and PubMed. Although I am used to the familiarity of searching MEDLINE on Dialog and the ease of searching it on Lexis/Nexis, I found the Web versions to be very attractive alternatives. Besides the cost advantage of Web searching, I am impressed by the ways in which NLM has made its MeSH headings available. With IGM and PubMed, it is very simple to find terms that will make up an accurate, comprehensive search. My experience has been that using the correct medical vocabulary is the most important factor when looking for medical information. Further, getting the actual articles has always been a time-consuming process. With the NLM Web products, the user merely has to point and click to order articles, some of which may be online.

However, both systems take a bit of practice. Maneuvering among the MeSH browser, pull-down menus, and various fields - i.e., defining and modifying the query - took time and was hard to keep track of. Differences between the two, while giving me more choices, also added to my confusion. But with practice, the user will find that PubMed and Internet Grateful Med are good vehicles with to search MEDLINE.

Before we leave NIH, let me mention MEDLINEplus, NLM's effort to make it easier for the general public to search MEDLINE (however, the information itself is not easier to understand). Launched in the fall of 1998, MEDLINEplus defaults to the PubMed Basic search screen. Users can also access medical dictionaries, directories, news, and other health government and non-governenment databases.

If MEDLINE is available in not one, but two, formats from NLM, why would a researcher choose to search it on a non-NLM Web site? One reason is convenience, especially if the user is already on another medical site that links to MEDLINE. Often the link is to either PubMed or Grateful Med. A more compelling reason is that some sites offer MEDLINE searching with a little extra added.

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Evaluated MEDLINE

Evaluated MEDLINE (I'll call it EM), found on the BioMedNet Website, is an example. BioMedNet calls itself an "online club" that targets the worldwide biological and medical research community. Produced by Electronic Press Limited, EM gets its name from experts' evaluations of articles that appear as links from selected MEDLINE records. EM also links to journals both within and outside of the BioMedNet Library. For a list of the journals within the BioMedNet Library, see http://biomednet.com/library. In addition, there are links from MEDLINE records to journal articles within the BioMedNet collection that cite them.

EM offers sophisticated MEDLINE searching, with Basic and Advanced screens and options that include Boolean searching, ordered proximity searching, and field searching. There is also a separate button for searching by MeSH headings. A very useful feature is the ability to combine previous searches and to keep a record of one's search history even after sign-off. A Table of Contents button allows browsing through the tables of contents of any of MEDLINE's journals.

Evaluated MEDLINE search results can be sorted by relevance or date. Full text links to articles, if available, are provided. Hard copy can be ordered online from the British Library Document Supply Center. A researcher may well choose to search Evaluated MEDLINE in order to take advantage of these features.

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Infotrieve

Infotrieve, a library services company that offers full-service document delivery databases on the Web, also offers FREE MEDLINE with point and click document ordering. The Infotrieve Online search engine allows the user to use either natural language or Boolean logic and field searching via pull-downs or field tags. Like Evaluated MEDLINE, FREE MEDLINE keeps a record of search queries and allows previous queries to be combined.

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HealthGate

Another commercial medical Web site with a slightly different take on MEDLINE searching is HealthGate, which provides free searching of MEDLINE and six other databases (AIDSDRUGS, AIDSLINE, AIDSTRIALS, CANCERLIT, and HealthSTAR). Enter a simple search in the box marked "Medline Search" or select Advanced searching. READER software matches natural language queries to MeSH headings. The Advanced screen accommodates Boolean logic and field restrictions.

HealthGate goes beyond MEDLINE in its coverage of the medical literature, and so do many other medical sites. The HealthGate Data Corp. both provides links to medical reference tools and supplies fulltext reference materials of its own. Some information is free; some is not. For example, through HealthGate, the researcher can search such non-NLM bibliographic databases such as EMBASE, PsycINFO, Age Line, and MDX Digests and retrieve titles of references for free. However, displaying detailed citations will entail a charge.

Full-text, fee-based medical sources on HealthGate include DIH: Drug Information, among others. Free full-text sources include Diagnostic Procedure Handbook with Key Word Index, by Robert K. Desai, et al. HealthGate publishes medical information as well; its Healthy Living Series is comprised of online articles on various topics and is free. To access both the free and fee-based sources, click on the appropriate button on the home page. HealthGate offers its members full access to its research databases and other information for a flat fee of $14.95 per month.

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MedConnect

MedConnect is another commercial site that provides free MEDLINE as part of its goal to be the "online hub for physicians and other health care professionals." It, too, goes beyond MEDLINE and has published its own medical information on the Web since 1994. MedConnect offers literature reviews, articles, journal clubs, board reviews, and teaching files. Articles written for MedConnect focus on emergency medicine, pediatrics, managed care, and primary care, although coverage of more topics is planned. MEDLINE can be searched using natural language or Boolean operators. Pull-down menus offer detailed field restrictors.

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Medscape

Medscape aims to "offer specialists, primary care physicians, and other health professionals the Web's most robust and integrated multi-specialty medical information and educational tool", although it plans to offer more consumer-oriented information in the future. It combines information from journals, medical news providers, medical education programs, and materials created for Medscape. Its real value is not so much access to MEDLINE as it is a collection of thousands of free, full-text, peer-reviewed clinical medicine articles that are searchable and produced for Medscape. Click on "Search Medscape" on the Home Page to bring up a screen for searching MEDLINE, Medscape's full-text articles, and various other databases such as Drug Information, Medical Images, a Medical Dictionary, and a Medical Bookstore. The latter is a searchable file of health-related textbooks available for purchase online, which would be very useful for identifying texts.

Three of Medscape's full text articles are relevant to this article. They discuss medical search engines and medical metasites. To find them click on "Medscape Full-Text" next to the query box and then enter "medical search engines."

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Medical Matrix

If you need a comprehensive guide to clinical medicine resources on the Internet, run, don't walk, to Medical Matrix.  This metasite annotates, evaluates and links to medical sites that "are relevant to the clinical practice of medicine, interesting to a general population, and easy to retrieve." An editorial board reviews and ranks all resources. For example, if you click on the "MEDLINE" button, you will see that Medical Matrix has links to over 15 MEDLINE sites, including Internet Grateful Med, PubMed and Evaluated MEDLINE. It also briefly describes each site and links to a very handy comparison chart. In addition the sites are ranked by a rating system of stars. PubMed has the highest rating, 5 stars. Clicking on "Rx Assist" at the top of the home page brought up a rated list of 28 Web sites on drugs. An explanation of the rankings is available.

To get an idea of the breadth of coverage available on Medical Matrix, I entered "panic disorder" in the Home Page search box. I got 172 hits. Each listing was linked to a specific web site; each listing was ranked. Users can also select to search the resources within a specialty or category found on the Home Page, which has 8 broad groupings, among them Specialties, Diseases, Clinical Practice, and Literature (including Hypertextbooks, journals, and MEDLINE). Each grouping has numerous subcategories. For example, when I clicked on "Psychiatry" under "Specialties", I got a long list of of ranked sites that were displayed by type of information: news, abstracts, texts, major sites, conference literature, directories, practice guidelines, online forums, patient education materials, and organizational resources. Medical Matrix provides the kind of one-stop shopping and searching that we see in FindLaw.

Hospitals, medical libraries, and professional associations that have a presence on the Web often provide links to sites that reproduce or index medical literature. In addition, the online catalogs of medical libraries are a window to the world of medical publishing. Medical/Health Sciences Libraries on the Web links to academic, hospital, and military medical libraries and many other medical sites in the U.S. and around the world. In addition, this site, produced by the University of Iowa Hardin Library for the Health Sciences, compiles the Hardin Meta Directory of Internet Health Sources, a directory of what it considers to be the best health-related sites on the web. They are arranged by medical specialty.

MedWeb, the medical metasite of Emory University's Health Sciences Library, is impressive for its links to health-related sites located around the world. You can enter subjects or keywords or you can select from a list of subject categories and then narrow your search.

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HealthWeb

HealthWeb "provides links to specific, evaluated information resources on the World Wide Web selected by librarians and information professionals at leading academic medical centers in the Midwest." Selection stresses quality and the content is directed toward both health care professionals and consumers. I clicked on the "Subjects" button and got a list by subject specialty; clicking on "Psychiatry" yielded links to 10 web sites plus brief annotations of each site. Searching can also be done by keyword. A keyword search of "anxiety" brought up 38 ranked web sites.

A product of the U.S. Department for Health and Human Services, healthfinder is a gateway to reliable consumer health and human services information. The medical researcher who clicks on "More Tools" will be rewarded with links to libraries, dictionaries, online journals, databases, foreign language resources, listservs, medical search engines and metasites.

When I do medical research, I usually try to find a plain English description of the topic before I start to search MEDLINE - and sometimes after. MedicineNet.com is a good place to go for understandable yet indepth medical information. Produced by a network of scientists and U.S. board certified physician writers, this site has hundreds of web articles on diseases, treatments, procedures, tests, and drugs.

Another site that seeks to make health care information accessible to a wide audience is InteliHealth, a joint venture of the Johns Hopkins University and Health System and Aetna US Healthcare. All information is reviewed and approved by Johns Hopkins, and more than 150 health care organizations, including NIH, are contributors. In addition, a section marked "Health Resources" includes links to physician and hospital locators, a drug research center, medical journals, databases (e.g., MEDLINE), health-related web sites, and MedCite, a user-friendly medical literature service that offers a topic-driven approach to MEDLINE. MedCite consists of the results for over 15,000 topics that have been searched by medical research librarians from the Johns Hopkins health science centers. Citations or abstracts to the 50 best articles are immediately accessible for each topic. All MedCite searches are updated and document delivery is available. If your topic is covered, it's like having a medical librarian on hand.

A medical search engine that I would like to mention is MedBot by Stanford University. MedBot brings together several types of resources: general search engines, medical indices, news sites, medical education, and medical imaging and multimedia sites. Some of these resources can be combined for a single Super Search; the user selects up to 4 databases to be searched at one time. Or, you can click on each category and search the listed sites one at a time.

The button marked "Medical Images and Multimedia Resources" underscores the fact that the research of medical sources is often a hunt for visual information. The fact that the Internet is not restricted to textual medical information makes it an extremely valuable research tool. Clicking on that button brings up query boxes for

  • WebPath, an electronic collection of 1900 images of pathology specimens along with text, tutorials, laboratory exercises, and examination items.
  • The Digital Anatomist, a collection of computer-generated images based on cryosection studies

When I tried to find some images, I was more successful in searching the above web sites directly from their home pages than I was in using MedBot. Entering "stomach" in the MedBot query box for WebPath brought up one hit. Entering stomach in the WebPath search box retrieved 36 items. I could also browse for images in WebPath by scrolling through a list of images grouped by categories such as General Pathology and Organ Systems Pathology.

Medscape also has compiled a file of medical images. Its search box allows the researcher to click on "Medical Images" and search for visual information. I entered "keratosis", which is a skin lesion, and got a thumbnail image. Clicking on the image brought up a screen-sized version with a caption and the source of the image.

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In conclusion, the Internet has become an important source of information in medicine and the health sciences, as it has in so many other areas. Medical information professionals are at the forefront of the effort to organize this vast, ever-increasing store of knowledge. The sites mentioned above reflect this effort and are meant to be a sampling of the marvelous tools that are now available to the medical researcher. Take some time to explore medicine on the Web; no doubt you'll discover many more.

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Footnotes

  1. For a discussion and review of medical information on the Internet, see articles in USA Today, July 14, 1999. <back to text>

  2. I am going to discuss selected Web sites. For an excellent, comprehensive introduction to medical research on the WWW, see "How to Search for Medical Information," by Frank Kellerman, Mary Zammarellli, and Robert Ballot. <back to text>

  3. There is some overlap among MEDLINE and these other databases, but the more specialized database usually provides greater coverage within a narrower topic. For example, AIDSLINE indexes monographs, scientific reports, and A/V materials as well as articles, but only those dealing with AIDS or HIV. <back to text>

  4. In PubMed, MeSH terms are automatically exploded if the MeSH field is selected; MeSH terms found using an "All Fields" search are not. <back to text>