This review examines the effect of publishing case reports on journal impact factor and future research. All case reports published in the four major English language oral and maxillofacial surgery journals in the two year period, 2007–2008, were searched manually. The citation data of each case report were retrieved from the ISI online database. The number, percentage and mean citations received by case reports and their relation to the 2009 journal impact factor were analysed. Case reports which received more than 5 citations were also identified and all of the citing articles retrieved and analysed. Thirty-one percent of all articles published in major oral and maxillofacial journals in 2007–2008 were case reports. Case reports had a low citation rate with a mean citation of less than 1. There were 38 (7.2%) case reports with more than 5 citations and 30% of the citing articles were also case reports. The publication of case reports negatively affected journal impact factor which correlated directly with the percentage of case reports published within a journal. Case reports reporting recent topics, describing new treatment/diagnosis method and with a literature review were more likely to receive citations.
A case report (CR) is the documentation in the scientific literature of a single clinical observation. CRs allow clinicians to share unusual, rare or new findings related to a disease or treatment, but they are considered to be the lowest level of evidence due to their anecdotal nature. With the increased advocacy of evidence based medicine (EBM), CRs are increasingly sidelined and assumed to have minimal impact on the management of patients. Advocates of CRs think they have significant value and impact within the medical literature. Their potential roles include describing new diseases, describing new treatments of known diseases, identifying the aetiology or mechanism of disease, recognizing rare manifestations of disease, detecting adverse/beneficial drug side effects, medical education, and audit.
Journal impact factor (IF) is a measure of the frequency with which the ‘average article’ in a journal has been cited in a particular year or period. It was developed by the Institute of scientific information (ISI) in the 1960s primarily as a bibliometric tool to assist libraries in selecting relevant journals for their holding. IF is derived by calculating the ratio between citations received in a particular year and the number of articles published in the two preceding years for a particular journal. IF increases with an increase in citations and a reduction in the number of articles published. The citation rates of CRs are often minimal so most major journals restrict or do not accept CRs because they may lower journal IF.
In the field of oral and maxillofacial surgery (OMS), CRs are generally published in all major journals of the specialty as a platform for sharing unusual events and treatments among peers. There are two important issues regarding CRs. The first, and most discussed, is the effect of publishing CRs on journal IF. Authors aim to publish in journals with the highest IF so that they are better rewarded by their institutions and research funding bodies. Journal editors seek to achieve the highest IF possible for their journal in order to attract the best manuscripts thus increasing the prestige of the journal and its parent organization or specialty. The second, more important but less prominent and less addressed, issue is the impact of CRs on the OMS specialty through their effect on future research and patient care in the long term. The aim of this study was to investigate both these aspects in order to describe the relevance of CRs to the OMS specialty.
Materials and methods
All CRs published in major English language OMS journals ( Table 1 ) from January 2007 to December 2008 were searched manually by the first author. The period was selected to assess the current situation while also giving enough time for any citing article to be published. The CRs were identified by screening the title and abstract of all published articles in 2007 and 2008 within each journal. The full text of articles was retrieved when data from the title/abstract were insufficient to make a decision. Only articles meeting the predefined criteria ( Table 2 ) were identified as CRs and included in the review.
|Major Oral & Maxillofacial Surgery Journals||2009 impact factor|
|Journal of Oral and Maxillofacial Surgery (JOMS)||1.580|
|International Journal of Oral & Maxillofacial Surgery (IJOMS)||1.444|
|British Journal of Oral & Maxillofacial Surgery (BJOMS)||1.327|
|Journal of Cranio-maxillofacial Surgery (JCMS)||1.252|
|1. No more than 5 patients|
|2. Full demographic and clinical background of each patient within the report|
|3. Must be citable by Institute for Scientific Information Web of Science (ISI)|
|4. Must be a full article (case reports within letters to editors, conference abstracts were not accepted)|
All CRs identified within the study period were classified as either: rare disease or pathology (RDP); or new treatment or diagnostic method (NTD). The ISI citation received by each CR was then retrieved from the ISI online databases. All the citation data were collected during the first week of August 2011 to ensure minimal changes to the number of citations over the time it took to conduct the study. Two different citation data were collected: citations received by the CR article in 2009; and total citations received by the CR from the date it was citable to the date of data collection (August 2011). The first citation data were used to answer the first objective (effect of CRs on journal IF) and the total citation rate was used for the second objective (impact of CRs on the OMS specialty). The data were entered into an Excel table. Any disagreements about selection or categorization of articles were resolved by discussion between the authors. The flow chart of the methodology is shown in Fig. 1 .
To assess the effect of publishing CRs on journal IF, the number/percentage of CRs published in each OMS journal and their relation to the journal IF were analysed. The relationships with IF were investigated in more detail by retrieving the total number and mean citations received by CRs in each OMS journal. The relation of type of CRs (RDP or NTD) and the effect of including a literature review in the CR on the citation rate were also investigated. CRs with the title containing the word ‘review’ were taken to include a literature review component within the article.
The impact of CRs on future research was determined by collecting data on the frequency in which CRs were cited from the day they were citable to the first week of August 2011. The number of citations was recorded. Subsequently, all CRs with more than 5 citations were selected and all of the citing articles retrieved. These CRs were categorized by topic and type (RDP or NTD). The citing articles were also examined regarding the type of study (randomized controlled trials (RCTs), systematic reviews (SRs), CRs, prospective study, retrospective case series, animal/laboratory study, editorial) by reviewing their title and abstracts and the citing journals IF. If more information was needed, the full text of the citing article was retrieved.
The effect of CRs on journal IF
During the period of study (January 2007–December 2008), BJOMS published the highest percentage of CRs of their total number of published articles while JCMS published the lowest percentage ( Table 3 ). Regarding the total number of CRs published, JOMS published the highest absolute number of CRs followed by BJOMS, IJOMS and JCMS ( Table 3 ). When the number of citations received by CRs was examined, a direct relationship was noted between the number of CRs published within a particular journal and the number of citations received ( Table 3 ). The journal with the highest number of CRs published had the highest overall citations of published CRs while the journal publishing the least number of CRs had the least overall citations of published CRs. When analysed in more detail, JCMS had the highest citation mean to the number of published CRs (0.82). This was followed by BJOMS, JOMS and IJOMS ( Table 3 ). None of the journals’ CRs citation mean reached the value 1.
|Journal||Year||CR articles||Total articles||CR/total article||Percentage CR/articles||Total CR citation 2009||Total article citation 2009||CR citation/CR article||Mean CR citation||2009 IF||IF without CR||Difference||% difference|
|BJOMS||2007||64||171||64/171||39%||53||247||53/64||0.83||471/355 = 1.327||361/202 = 1.787||0.46||34.7%|
|IJOMS||2007||51||183||51/183||28%||39||353||39/51||0.76||553/383 = 1.444||491/276 = 1.779||0.335||23.2%|
|JCMS||2007||14||58||14/58||24%||14||88||14/14||1||154/123 = 1.252||132/96 = 1.375||0.123||9.8%|
|JOMS||2007||118||415||118/415||28%||95||843||95/118||0.81||1300/823 = 1.58||1160/584 = 1.99||0.41||26.0%|