ARTHRITIS & RHEUMATISM Vol. 58, No. 2, February 2008, pp S153–S159 DOI 10.1002/art.23169 © 2008, American College of Rheumatology What Journal Citations Teach Us About Rheumatic Diseases Steven K. Magid, Timothy R. Roberts, and Mohsen Javaheri The past 50-plus years have seen dramatic ad- vances in medical discovery. Only 51 years have elapsed from the identification of the double-helix structure of DNA (1) to the publication of the first estimate of the human genome (2). Furthermore, the specialty of rheu- matology is also relatively new. The name “rheumatol- ogist” was first introduced in 1940 by Bernard Comroe (3,4), and the first subspecialty board exams took place in 1971. As a field of study, rheumatology changed radically in the early 1950s largely because of the discoveries of rheumatoid factor, the lupus erythemato- sus cell, and the therapeutic effect of cortisone (4). Keeping pace with medical discovery has been an exponential increase in the volume of published litera- ture, as well as a dramatic improvement in the technol- ogy available to search this literature. The PubMed database contains over 16 million citations published between 1951 and 2005. This is remarkable considering the fact that the National Library of Medicine’s Index- Cat (a database for citations older than those available in PubMed) lists only 2.5 million references to publica- tions from late 17th to the early 20th centuries. The ability to access over 50 years of publication data electronically with uniform indexing, paired with scientific developments, invited our approach to exam- ining publication trends in the field of rheumatology. We were interested in studying how the number of articles on particular topics changed over time. We theorized that a number of patterns would be displayed that would reflect the history of our specialty. PubMed search We reviewed the indices of Arthritis & Rheuma- tism (A&R) from volume 1 (1958) to the present and developed a list of diseases and concepts considered central to the field of rheumatology. These terms were searched in PubMed. For all but two searches, we allowed PubMed’s automatic term mapping to enhance the terms entered (Table 1). This function searches the database not only for the phrase entered as text in the title or abstract of the citation, but it also maps the phrase to the appropriate Medical Subject Heading (MeSH). For example, the search for superantigen in PubMed mapped to the MeSH term Superantigens and performed a search that included all articles indexed with that term. Nearly 25% of the citations in the resulting set did not have the words superantigen or superantigens in the title or abstract. Additionally, the subject headings are automatically “exploded,” meaning that if a term has corresponding specific subject head- ings within the MeSH tree structure, these headings are included in the search. For example, the phrase rheuma- toid arthritis automatically maps to the MeSH term Arthritis, Rheumatoid and includes citations with the more specific subject headings of Arthritis, Juvenile Rheumatoid; Caplan’s Syndrome; Felty’s Syndrome, etc. Automatic term mapping was deemed inade- quate for two of the searches: the illnesses associated with silicone breast implants and rapeseed oil poisoning. For these topics, we constructed more complex searches using subject heading combinations to retrieve a repre- sentational result set. Also, although we used the auto- matic term mapping for our search on fibromyalgia, we did not count citations before 1981, the year that the word was first used by an author in an article title (5). The subject heading fibromyalgia has been retroactively assigned to citations that were previously assigned the heading fibrositis. For the purpose of our study, includ- ing those results would have misrepresented the trend. Separate searches were performed for consecu- tive 5-year periods, from 1951 through 2005. (We per- formed our searches between May 1, 2007 and Septem- ber 16, 2007.) For each topic, the total number of papers was tabulated for each 5-year period and was then charted over time as: absolute number of articles, per- centage of the total number of PubMed articles, and the percentage of PubMed “rheumatic disease” articles. To Steven K. Magid, MD, Timothy R. Roberts, MLS, Mohsen Javaheri, MD: Hospital for Special Surgery, New York, New York. Address correspondence to Steven K. Magid, MD, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021. E-mail: magids@hss.edu. Submitted for publication September 17, 2007; accepted September 17, 2007. S153