Ways to find medical information on the Internet

Contents of this page:

1. Introduction and context
2. Searching the network for medical information
   • WWW documents
   • Journals and books
   • People and institutions
   • Communication
   • Software
   • Events
3. Searching medical databases
   • Medline
   • Other literature databases
   • Factual databanks
4. Evidence-based medicine
5. Image databanks
6. Sources of further help
7. Your comments

1. Introduction and context

This page aims to give you a brief overview and some starting points for finding medical and health sciences information on the Internet. It includes World Wide Web, electronic mail and other networked resources such as Medline.

When you plan to find some information you should follow a four-stage process:

• Choose the most appropriate place to look
• Develop an effective search strategy
• Carry out the search
• Critically evaluate the results obtained

Choose the most appropriate place

There is a great deal of useful information on the internet, some of it unique (i.e. only available on the internet) and some of it replicating printed resources. However, it is still true that many valuable information resources are only available, or are more easily available, in print or through local institutional arrangements. Do not assume that the Internet is always the best place to start looking! Your search will be quicker if you start looking where there is a good chance of success.

Develop a search strategy

You should identify the main concepts associated with your question. For example, if you are interested in "asthma", you should be explicit - is it childhood asthma? is it drug therapy for asthma? All of these? Then generate terms to search for, allowing for spelling and terminology variations. Try to think of synonyms and closely related terms. Then make sure you are clear about the relationships between these terms and concepts before actually starting to search - decide which concepts are the most important ones. If your search retrieves too much or too little you will need to broaden or narrow the focus of your search. Decide how you might do this (e.g. by date, by geography, by resource type).

Carry out the search

The actual mechanics of carrying out a search is the easiest part. Make use of the help facilities provided by the search system you are using, and also of any local assistance (e.g. in your library). You may be able to obtain support via email from your local library, or from the maintainers of the system you are using.

Critically evaluate

You should adopt a critical approach to search results - to any search results but especially to Internet resources. Much has been written about this, but the best tip is to look at the source of the information when deciding how reliable it is. This is particularly crucial when adopting an evidence-based approach. You should also be critical of your search strategy and the resource you are using. How confident are you that you have found the best answer to your question, particularly if you find only a small number of documents? Don't be afraid to amend your strategy and search a second, third, fourth time.

2. Searching the network for medical information

What's there ?

The Internet is a complex mixture of many kinds of information; it is not at all homogeneous. Universities and research institutions provide information about their teaching and research programs. Specialised service centres give access to research databases. Governments and other official bodies (e.g. the World Health Organisation) publish information about their programs and policies. Commercial organisations provide customer support and advertising information. Professional bodies provide information for their members. Medical charities and support groups make their information available. Individuals publish details of their work and interests. Increasingly, the information industry is also using the Internet to sell access to information, including "traditional" information sources like bibliographic databases and journals. Remember that looking at the origin of an information resource can be a guide to its reliability.

Some examples of WWW sites of major medical importance are the World Health Organisation, the US Department of Health and Human Services (including the National Library of Medicine and CancerNet from the National Cancer Institute), the Cochrane Collaboration and the Virtual Hospital.

WWW documents

There are many services that can help you to find relevant documents on the World Wide Web (WWW). Unfortunately many of these services also find irrelevant and trivial documents. There are several kinds of search services: subject gateways, virtual libraries, indexing engines and meta-search engines.

TIP: Try one of the subject gateways first. If that fails to locate what you need then search one of the indexing engines. More information about using them is available here. For very rare subjects use a meta-search engine.

Subject gateways

These are subject-specific, and well-organised collections of resources that have been carefully selected for relevance and quality. They index at the level of a specific well-defined information resource, either a document or a service.

A longer list of gateways is at the OMNI Launch Pad.

Virtual Libraries

These are more selective and more organised than the indexing engines, but less selective than subject gateways. They tend to be bigger than subject gateways but add less value (in terms of indexing, descriptions etc). There are also some that cover only a narrow subject area (e.g. Neurosciences, Orthopaedics). All these services usually index at the level of an entire web site.

Indexing engines

Powerful indexing engines index millions of documents on the network. They are very comprehensive but do not discriminate by subject or quality and do not organise the documents. Bigger is not necessarily better! You can search but not browse. These search services index at the level of a web page rather than an entire document.

Meta-search engines

These have developed in response to the proliferation of indexing engines. A meta-search engine will send your search to multiple index sites and produce a single list of results. Some of them will also eliminate duplicate results. They are useful where you need to carry out a very comprehensive search quickly. However, because each search engine has slightly different search features, you need to be careful when formulating any but the most simple search.

Journals and books

Journals

A large number of journals are now available in some form on the WWW - tables of contents, abstracts, or complete articles. Increasingly it is necessary to have a subscription in order to access the complete text of articles on-line, though some journals make the electronic version free to subscribers to the printed version. You should ask your Hospital or University library about this. A useful list of biomedical journals on the web is maintained.

Books

While there are as yet few electronic books available on the web there are many library catalogues and publishers' catalogues which can be searched to find or verify details of books. You can also use the services of some Internet bookshops to find current details of books and to order them. Blackwells, Amazon and Dillons all have such services.

People and Institutions

Trying to find email addresses or other contact details via the web can be a frustrating experience. If the person you're seeking is in a sector/country where Internet use is quite pervasive (e.g. a North American University) then you have a good chance of success. There are some general directories, but if you know the person's institution, or know that they are a member of a particular professional society, then you should start by looking for a directory on that institution or society's WWW site. Often the best way is to contact the person by phone or fax first and ask their email address.

Communication - email lists and Usenet newsgroups

Electronic communication can be a very good way of making contact with colleagues across the world (or even across the corridor). Electronic mail discussion lists and Usenet newsgroups make it easy to discuss topics of interest with like-minded people, to ask questions of a group of experts or to make announcements. Some lists of medical newsgroups and biological newsgroups are available as well as the Kovacs directory and the Liszt directory.

Software

The Internet contains many "anonymous ftp archives". These are sites which are open to all and contain files, usually of software. The best general way to search for software held in Internet ftp archives is to use Archie. One very simple version of Archie is the Archieplex interface, that provides a WWW form to fill in and do your search.

Events

There is no single authoritative listing of medical conferences and events. One useful one is TechExpo; another is MedicalConferences.

3. Searching medical databases

The most important database of medical literature is Medline, but there are many other valuable literature databases and a number of specialised factual databanks.

Medline

Medline (produced by the National Library of Medicine in the USA) has been available via computer for many years. There are now many different ways of accessing Medline - some free, some charged; some open access, some restricted; some very basic, some very powerful. Many University and Hospital libraries provide networked access to Medline throughout the institution (either using the WWW or a special client program) and this can be the most effective way of accessing Medline.  If you do not have that option then a free Medline service may be useful, but some of these  provide only very limited searching facilities.  Searching Medline effectively for subjects is difficult with some very simple interfaces that cannot access the full power of Medline indexing. The  National Library of Medicine provide free access to two versions of Medline via the WWW:  PubMed and Internet Grateful Med (IGM).  Further information about both of these is available.  PubMed provides a very useful "related records" feature, while IGM has a more effective search interface.   Another good version is available from BioMedNet.  You need to register to use this service but there is no charge for that.  BioMedNet's version includes evaluations of some articles, and also has the "related records" feature.  A number of commercial services also offer access to Medline with more powerful search interfaces.  Two widely-used services are from OVID and SilverPlatter - you should contact these companies directly for more information (but ask your local library service first in case there is already access within your institution).  A good comparison of Medline  versions  is available at OMNI's Medline on the Internet page.

Other literature databases

Although Medline is the most widely used database, there are many others that can be useful, such as those in the table below.  These may be available through your University or Hospital library but if not then it will probably be necessary to register and pay to use them. In the UK academic sector these are available to subscribing institutions via the BIDS service or the EDINA service. The long-established commercial datahosts Dialog and Datastar  provide access to a wide variety of biomedical databases and both can be used via the web.  OVID and SilverPlatter also provide access to some of these databases.

Factual databanks

The Human Genome Project generates enormous quantities of data most of which is available freely via the Internet. Gene and protein sequences, protein structures, complete genome sequences and disease linkage information can be found in a myriad of specialised databases. A good directory of these is at the Human Genome Mapping Project Resource Centre. More background information is also available. Most of the major databases are available in a number of miirror sites around the world; the UK site has been given in most cases below.

4. Evidence-based medicine

The major resources for evidence-based medicine are contained in the Cochrane Library - you can subscribe to this on CDROM or via the Internet. Abstracts are available for free on the web. A number of guides to potentially useful web sites have been produced; some of the most useful are listed below.

5. Image databanks

Making medical images available via the WWW presents challenges due to copyright problems and ethical problems (i.e. obtaining patient consent). The MIDRIB project is trying to tackle these problems and is a good source of expertise. The NLM's pioneering collection is a valuable resource, but has an historical mission. The NLM has also created the Visible Human, which now has a mirror in the UK. The Bristol Biomedical Image archive requires users to register before downloading images, anyone may search and view thumbnails. There are many smaller collections - these can be found by searching subject gateways or search engines. HotBot allows you to limit a search to "media type" of image.

6. Further sources of help

Information about the WWW and the Internet is available from many sources. Your local computing service or library may be able to help you get started on the WWW, but a good deal of training and reading materials are available on the WWW itself. The Big Dummy's Guide is a very useful entry-level introduction to the Internet. The WWW organisation, responsible for overseeing the WWW as a whole, provides an overview of the WWW project. The presentation slides and notes from a workshop given at Mednet 97 - "Finding Medical Information on the Internet" complement this guide to resources. Several recent books on the subject are available:

• Medicine and the Internet: Introducing Online Resources and Terminology
• Medical Information on the Internet : a guide for health professionals
• The Internet for physicians
• The Internet for nurses and allied health professionals
• Computers in Nursing's Nurses' guide to the Internet

7. Your comments

Because the Internet is so vast and is changing so fast, this document is probably out of date as soon as it is published. If you find any inaccuracies or omissions please contact Frank Norman, stating clearly that it is this page you are referring to and which section you are commenting on. If you have a question about this page, please explain clearly what you need to know, what resources you have already tried (e.g. your local library) and where you are based.