Wikipedia:Identifying reliable sources (medicine)
![]() | This page documents an English Wikipedia content guideline. Editors should generally follow it, though exceptions may apply. Substantive edits to this page should reflect consensus. When in doubt, discuss first on the talk page. |
![]() | This page in a nutshell: Ideal sources for biomedical material include literature reviews or systematic reviews in reliable, third-party, published secondary sources (such as reputable medical journals), recognised standard textbooks by experts in a field, or medical guidelines and position statements from national or international expert bodies. Cite reviews, don't write them. |
Biomedical information must be based on reliable, third-party published secondary sources, and must accurately reflect current knowledge. This guideline supports the general sourcing policy with specific attention to what is appropriate for medical content in any Wikipedia article, including those on alternative medicine. Sourcing for all other types of content – including non-medical information in medicine-articles – is covered by the general guideline on identifying reliable sources.
Ideal sources for biomedical information include: review articles (especially systematic reviews) published in reputable medical journals, academic and professional books written by experts in the relevant fields and from respected publishers, and guidelines or position statements from national or international expert bodies. Primary sources should generally not be used for medical content, as such sources often include unreliable or preliminary information; for example, early lab results that do not hold in later clinical trials.
See the reliable sources noticeboard for questions about reliability of specific sources, and feel free to ask at WikiProjects such as WikiProject Medicine and WikiProject Pharmacology.
Definitions
editTypes of sources
editIn the biomedical literature:
- A primary source is one in which the authors directly participated in the research and documented their personal experiences. They examined the patients, injected the rats, ran the experiments, or supervised those who did. Many papers published in medical journals are primary sources for facts about the research and discoveries made.
- A secondary source summarizes one or more primary or secondary sources to provide an overview of current understanding of the topic, to make recommendations, or to combine results of several studies. Examples include literature reviews or systematic reviews found in medical journals, specialist academic or professional books, and medical guidelines or position statements published by major health organizations.
- A tertiary source summarizes a range of secondary sources. Undergraduate- or graduate-level textbooks, edited scientific books, lay scientific books, and encyclopedias are tertiary sources.
Biomedical v. general information
editBiomedical information requires sourcing that complies with this guideline, whereas general information in the same article may not.
For example, an article on Dr Foster's Magic Purple Pills could contain both biomedical and non-biomedical claims:
- Dr Foster's pills cure everything. A biomedical claim! Strong MEDRS (MEDical Reliable Source) sourcing is definitely required here (see WP:MEDASSESS)
- The pills were invented by Dr Archibald Foster and released onto the market in 2015. This is not biomedical information, and it only requires ordinary RS
- They are purple and triangular, packaged one to a box,[citation needed] as no-one ever manages to swallow a second one.[medical citation needed]
Basic advice
editAvoid primary sources
editPer the Wikipedia policies of neutral point of view, no original research, and verifiability, articles need to be based on reliable, independent, published secondary or tertiary sources. For biomedical content, the Wikipedia community relies on guidance contained in expert scientific reviews and textbooks, and in official statements published by major medical and scientific bodies. Note that health-related content in the general news media should not normally be used to source biomedical content in Wikipedia articles. (News sources may be useful for non-biomedical content, such as information about "society and culture" – see WP:MEDPOP.)
Primary sources should NOT normally be used as a basis for biomedical content. This is because primary biomedical literature is exploratory and often not reliable (any given primary source may be contradicted by another). Any text that relies on primary sources should usually have minimal weight, only describe conclusions made by the source, and describe these findings so clearly that any editor can check the sourcing without the need for specialist knowledge. Primary sources should never be cited in support of a conclusion that is not clearly made by the authors (see WP:Synthesis).
Respect secondary sources
editPrimary sources should not be cited with intent of "debunking", contradicting, or countering conclusions made by secondary sources. Synthesis of published material advancing a position is original research, and Wikipedia is not a venue for open research. Controversies or uncertainties in medicine should be supported by reliable secondary sources describing the varying viewpoints. Primary sources should not be aggregated or presented without context in order to undermine proportionate representation of opinion in a field. If material can be supported by either primary or secondary sources – the secondary sources should be used. Primary sources may be presented together with secondary sources.
Findings are often touted in the popular press as soon as primary research is reported, before the scientific community has analyzed and commented on the results. Therefore, such sources should generally be omitted (see recentism). Determining weight of studies requires reliable secondary sources (not press releases or newspaper articles based on such sources). If conclusions are worth mentioning (such as large randomized clinical trials with surprising results), they should be described appropriately as from a single study:
"A large study published in 2010 found that selenium and Vitamin E supplements, separately as well as together, did not decrease the risk of getting prostate cancer and that vitamin E may increase the risk; they were previously thought to prevent prostate cancer." (citing PMID 20924966)
Given time a review will be published, and the primary sources should preferably be replaced with the review. Using secondary sources then allows facts to be stated with greater reliability:
"Neither vitamin E nor selenium decreases the risk of prostate cancer and vitamin E may increase it." (citing PMID 29376219, PMID 26957512)
If no reviews on the subject are published in a reasonable amount of time, then the content and primary source should be removed.
A reason to avoid primary sources in the biomedical field – especially papers reporting results of in vitro experiments – is that they are often not replicable[1][2][3] (see also replication crisis) and are therefore unsuitable for use in generating encyclopedic, reliable biomedical content. Scientists at Bayer reported in 2011 that they were able to replicate results in only ~20 to 25% of prominent studies they examined;[4] scientists from Amgen followed with a 2012 publication showing that they were only able to replicate 6 (11%) of 53 high-impact publications and called for higher standards in scientific publishing.[5] Further, the fact that a claim is published in a refereed journal need not make it true. Even well-designed randomized experiments will occasionally produce spurious results. Experiments and studies can produce flawed results or even fall victim to deliberate fraud (e.g. the Retracted article on dopaminergic neurotoxicity of MDMA and the Schön scandal.)
Summarize scientific consensus
editScientific journals are the best place to find both primary and secondary sources. Every rigorous scientific journal is peer reviewed. Be careful of material published in journals lacking peer review or that report material mainly in other fields. (See: Martin Rimm.) Be careful of material published in disreputable journals or disreputable fields. (See: Sokal affair.)
Wikipedia policies on the neutral point of view and not publishing original research demand that we present prevailing medical or scientific consensus, which can be found in recent, authoritative review articles, in statements and practice guidelines issued by major professional medical or scientific societies (for example, the European Society of Cardiology or the Infectious Disease Society of America) and widely respected governmental and quasi-governmental health authorities (for example, AHRQ, USPSTF, NICE, and WHO), in textbooks, or in scholarly 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. Additionally, the views of tiny minorities need not be reported.
Finally, make readers aware of controversies that are stated in reliable sources. A well-referenced article will point to specific journal articles or specific theories proposed by specific researchers.