Case reports: Essential or irrelevant?

Does the medical literature need more case studies? A new journal is betting it does, even as editors at other journals say the answer is no.

Historically, case reports have proven extremely valuable to clinicians faced with diseases they knew little about. But in an age where countries spend more on research than ever before investigating both rare and common diseases, some experts argue that the obscure nature of many case reports makes them of little value to the average practitioner.

Case reports typically receive fewer citations than research articles, putting them in danger of being phased out at journals where citation data rule decisions, said Matthew Cockerill of BioMedCentral (BMC, sister company to The Scientist), which publishes the new online open access journal, The Journal of Medical Case Reports.

Indeed, a 2005 study in the Journal of the American Medical Association showed that case reports receive the fewest citations of all other study designs. In a group of 416 case reports published between 1991 and 2001, less than two percent received 10 or more citations in the first two years of publication.

Dedicating an entire journal to case reports ensures that these valuable stories will be told, and grouping them together helps doctors establish timelines or patterns for rare pathologies, Cockerill noted.

However, Drummond Rennie, deputy editor of the Journal of the American Medical Association -- a journal that does not publish case reports -- said he is skeptical about the value of the new journal. Case reports that merely add another patient to a roster of those who have rare diseases accomplish little in the medical literature, he told The Scientist. The role of journals is "to advance knowledge," he added. "The first few cases [of a rare condition] are great, someone had to describe it. After that they have to say why they got [the condition] and what are we going to do about it."

A press release heralding the new journal noted that the number of published case reports is declining, based on searches of PubMed for individual journals. Cockerill, for instance, said a search for case studies in the British Medical Journal yielded 149 case reports in 1990, and only 37 in 2005. However, The Scientist replicated Cockerill's search -- using the terms "BMJ [All Fields]" and "Case Reports [ptyp]" -- and found the same total numbers as Cockerill, but some of the citations were not case reports.

According to Matthew Falagas, associate professor at Tufts University School of Medicine, who wrote an article assessing case reports in the American Journal of Medicine in 2005, anecdotal reports are valuable, and decreasing. "The number of case reports is declining, I'm certain of it, from reading the literature for 25 years," he told The Scientist.

Many journal editors contacted by The Scientist agreed that case studies have a somewhat limited value to general readers, but all said they continue to publish the reports, and have no plans to stop.

The British Medical Journal does not publish traditional case studies, but includes about one case report a month under the educational section "Practice," which presents case reports in a particular format. "The reason for not publishing case reports other than in this format is that for a general medical audience we see little benefit from anecdotal reports, unless there is something specific to learn from them," Fiona Godlee, deputy editor of the BMJ told The Scientist in an Email. Godlee did not respond by deadline to Cockerill's claim that the BMJ is publishing fewer case reports than in previous years.

The Lancet publishes one case report every week. "We regard them as educationally of value," Astrid James, deputy editor of The Lancet told The Scientist in an Email. "We have seen no decline in our submissions, and intend to continue publishing them."

Editors at the New England Journal of Medicine believe case studies serve as teaching devices, Karen Pederson, media relations manager of the NEJM, told The Scientist in an Email. "They do not necessarily introduce new disorders or new understanding of a known disorder," she added. "But I do not think there has been any kind of decrease [in the number we publish], and a quick survey of our editors says that they agree."

A PubMed search by The Scientist, using the terms "New England Journal of Medicine [All Fields]" and "Case Report [ptyp]", retrieved 200 articles in 2005, the same amount as in 1990. Although it's unclear whether the proportion of case studies relative to other articles has changed, a search of Web of Science using the term "case report" retrieved 160 articles in 1953 and 4,011 in 2006.

According to Joseph Alpert, editor in chief of The American Journal of Medicine, some case reports are more valuable than others. Outlier case reports -- the rare conditions that most doctors won't see-- are of "limited benefit to the active, practicing internist," he wrote in an editorial this month. Case reports that present unusual characteristics of a more common condition tend to be more valuable, Alpert noted. The American Journal of Medicine continues to publish a small number of case reports, Alpert told The Scientist in an Email.

Cockerill argued that even the highly unique and specific outlier case report can be valuable to both researchers and clinicians -- signaling adverse drug interactions or symptoms of disease that may be overlooked otherwise, for instance.

The Journal of Medical Case Reports has received 190 submissions since the end of last year, when it began accepting submissions, and has published 19 case reports since February.

Does the medical literature need more case studies? Tell us here.

Andrea Gawrylewski
mail@the-scientist.com

Links within this article:

G. McGee, "The plural of anecdote is not Ambien," The Scientist, October 2006.
http://www.the-scientist.com/article/display/24842

Matthew Cockerill
http://www.biomedcentral.com/info/about/whoweare

Journal of Medical Case Reports
http://www.jmedicalcasereports.com/

N. Patsopoulos et al, "Relative citation impact of various study designs in the health sciences," JAMA 293:2362-2366. May, 2005.
http://www.the-scientist.com/pubmed/15900006

Matthew Fagalas
http://whitepages.tufts.edu/ldapentry.cgi?tuftsedutrunk=476F57A77EE9C346EDDC06D46D9E58DC

M. Falagas et al "An analysis of the Massachusetts General Hospital case records (1994-2004)," Am J Med, 118:1452-1452, December, 2005.
http://www.the-scientist.com/pubmed/16378826

J. Alpert, "White crows and Aesop's fables,"Am J Med, 120:379, May, 2007.
http://www.the-scientist.com/pubmed/17466642