Wikipedia:Identifying reliable sources (medicine)

See also: Wikipedia:Reliable sources and Wikipedia:No original research.

Wikipedia's medical articles, while not a source of medical advice, are nonetheless an important health information resource. Therefore, it is vital that medical articles be based on reliable published sources. These guidelines supplement the general guidelines at Wikipedia:Reliable sources with specific attention to sources appropriate for medical and health-related articles. The ideal source for such articles would be a general or systematic review in a reputable medical journal, or a widely recognised standard textbook written by experts in a field. It is also useful to reference seminal papers on the subject to document its history and provide context for the experts' conclusions.

Some definitions and basics

• A primary source in medicine is one where the authors participated in research or documented their personal experiences. They examined the patients, injected the rats or filled the test tubes, or at least supervised those who did. Many, but not all, papers published in medical journals are primary sources. Most medical journals have high editorial standards and ensure research papers are peer reviewed.

• A secondary source in medicine summarizes one or more primary or secondary sources, usually to give an overview of the current understanding of a medical topic. Review articles and specialist textbooks are examples of secondary sources. A good secondary source from a reputable publisher will be written by an expert in the field and be editorially or peer reviewed. Journalists writing in the popular press, and marketing departments who issue press releases, tend to write poorer secondary source material; however, such material may be appropriate for inclusion in some contexts.

• A tertiary source usually summarizes secondary sources. Encyclopedias, including Wikipedia, are tertiary sources.

In general, Wikipedia's medical articles should be based upon published, reliable secondary sources whenever possible. Reliable primary sources should be used with great care because of the potential for misuse. For that reason, edits that rely on primary sources should only make descriptive claims that can be checked by anyone without specialist knowledge. Where primary sources are cited, they should be presented in a manner which hews closely to the interpretation given by the authors or by published, reliable secondary sources. Primary sources should not be cited in support of a conclusion which is not clearly adduced by the authors or by reliable secondary sources, as defined above (see Wikipedia:No original research).

Using primary sources to "debunk" the conclusions of secondary sources

Individual primary sources should not be cited or juxtaposed so as to "debunk" or contradict the conclusions of reliable secondary sources, unless the primary source itself directly makes such a claim (see Wikipedia:No original synthesis) Controversies or areas of uncertainty in medicine should be illustrated with reliable secondary sources describing the varying viewpoints.

Cite peer-reviewed scientific publications and check community consensus

Scientific journals are the best place to find primary source articles about experiments, including medical studies. Any serious scientific journal is peer-reviewed. Be careful of material in a journal that is not peer-reviewed reporting material in a different field. (See the Marty Rimm and Sokal affairs.)

The fact that a statement is published in a refereed journal does not make it true. Even a well-designed experiment or study can produce flawed results or fall victim to deliberate fraud. (See the Retracted article on neurotoxicity of ecstasy and the Schön affair.)

Neutrality and no original research policies demand that we present the prevailing medical or scientific consensus, which can be found in recent, authoritative review articles or textbooks and some forms of monographs. Although significant-minority views are welcome in Wikipedia, such views must be presented in the context of their acceptance by experts in the field. The views of tiny minorities need not be reported. (See Wikipedia:Neutral Point of View.)

Make readers aware of any uncertainty or controversy. A well-referenced article will point to specific journal articles or specific theories proposed by specific researchers.

In science, avoid citing the popular press

The popular press generally does not cover science well. Articles in newspapers and popular magazines generally lack the context to judge experimental results. They tend to overemphasize the certainty of any result, for instance presenting a new experimental medicine as the "discovery of the cure" of a disease. Also, newspapers and magazines frequently publish articles about scientific results before those results have been peer-reviewed or reproduced by other experimenters. They also tend not to report adequately on the methodology of scientific work, or the degree of experimental error. Thus, popular newspaper and magazine sources are generally not reliable sources for science and medicine articles.

What can a popular-press article on scientific research provide? Often, the most useful thing is the name of the head researcher involved in a project, and the name of his or her institution. For instance, a newspaper article quoting Joe Smith of the Woods Hole Oceanographic Institution regarding whales' response to sonar gives you a strong suggestion of where to go to find more: look up his work on the subject. Rather than citing the newspaper article, cite his published papers.

Assess the quality of evidence available

Several systems exist for assessing the quality of available evidence on medical subjects, and these should be kept in mind while assessing whether a particular viewpoint is a majority or minority one, and in deciding what constitutes evidence-based medicine.

Two of the most commonly used schemes are the US Agency for Healthcare Research Quality one:

Class	Requirements
Ia	Evidence from meta-analysis of randomised controlled trials (RCTs)
Ib	Evidence from at least one RCT
IIa	Evidence from at least one well-designed controlled study without randomisation
IIb	Evidence from at least one other type of well-designed quasi-experimental study
III	Evidence from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies, and case control studies
IV	Evidence from expert committee reports or opinions and/or clinical experience of respected authorities

And the slightly simpler NHS one:

Grade	Evidence	Description
A	Ia, Ib	Requires at least one RCT as part of the body of literature of overall good quality and consistency addressing the specific recommendation
B	IIa, IIb, III	Requires availability of well-conducted clinical studies but no RCTs on the topic of recommendation
C	IV	Requires evidence from expert committee reports or opinions and/or clinical experience of respected authorities. Indicates absence of directly applicable studies of good quality.

Case reports, whether in the popular press or a peer-reviewed medical journal, are a form of anecdote and generally fall below the minimum requirements of either scheme.

Periodicals

Periodicals include newspapers, magazines and journals. The very latest research is often published first here. Where an archive is provided however, then many decades of research can be accessed.

Medical journals

These are a natural choice as a source for up-to-date information for medical articles. They contain a mixture of primary and secondary sources, as well as less technical material such as biographies. Although almost all such material will count as a reliable source, not all the material is equally useful.

Core journals

Impact factor is a crude guideline to a journal's authority.[1] If the articles in the top journals tend to be cited most often by other expert authors, then it is not a bad idea to do likewise on Wikipedia. The core general medical journals include

• New England Journal of Medicine
• The Lancet
• Journal of the American Medical Association (JAMA)
• Annals of Internal Medicine
• British Medical Journal (BMJ)
• Canadian Medical Association Journal

Core basic science and biology journals include

• Science
• Cell
• Nature

Additionally, an authoritative bibliograpy of medical books and journals recommended by medical librarians is the Brandon/Hill Selected List of Print Books and Journals. [2]

Article type

Journal articles come in many types: original research, reviews, editorials, book reviews, correspondence, biographies and eulogies. Research papers are, of course, primary sources. A general review of a subject by an expert in the field makes a good secondary source. Such reviews often contain no original research but can make interpretations and draw conclusions from primary sources that no Wikipedia editor would be allowed to do. A systematic review is both a primary and secondary source—it summarizes other papers but it does so in order to research the field and possibly come to a novel conclusion.

Popular science

Popular science magazines such as New Scientist and Scientific American sometimes feature articles on medical subjects. Whilst not peer reviewed, their advantage is that the material is explained in plain English.

Newspapers

Quality newspapers can make a good source for social, biographical, current-affairs and historical information in a medical article. They should not be used as a source for medical facts and figures.

Books

Medical textbooks

Medical textbooks published by the academic press are an excellent secondary source. Ensure the book is up-to-date, unless a historical perspective is required.

Popular science and medicine books

These are usually tertiary sources, but there are exceptions. Self-published or books published by vanity presses are generally not subject to any form of independent fact-checking or peer review and may not be reliable sources.

Online

Reliable references

• OMIM provides a lot of useful info with regards to genetic diseases.
• eMedicine is a comprehensive and reliable source.
• WhoNamedIt is an excellent reference for eponyms in medicine.

Background reading

• MedlinePlus has encyclopedic content in plain English from the NIH.
• Diseases Database.
• GPnotebook is a UK website which provides an easy access for general practitioners and may be an interesting source.
• SUNY Downstate Medical Center has an excellent set of online anatomic preparations.
• Merck Manual Home and Professional edition