title: The evolution of academic performance in emergency medicine journals: viewpoint from 2000 to 2009 journal citation reports.
abstract: OBJECTIVE
  Emergency medicine (EM) is a young but rapidly growing field. An evaluation of academic performance and the growing impact of EM journals would help to elucidate the increase in the number of EM scientific studies. The authors used the Journal Citation Reports (JCR) database to investigate the scientific achievements of EM journals in the past 10 years.
  
  
  METHODS
  This was a literature review study. All data were collected from the JCR database. Journals listed in the EM category from 2000 to 2009 were included. Eleven categories that were considered most closely related to EM by a consensus of the authors were chosen for comparison, including cardiac and cardiovascular systems, clinical neurology, critical care medicine, gastroenterology and hepatology, infectious diseases, general and internal medicine, pediatrics, respiratory system, surgery, toxicology, and urology and nephrology. Data on journals in the EM category were collected, including journal title, language, journal country or territory, impact factor for each year, total number of EM journals for each year, and the EM category aggregate impact factor (available from 2003 to 2009). The variables in the comparison group included the number of journals in each of the 11 clinical medicine categories from 2000 to 2009 and the aggregate impact factors for 2003 to 2009. The category aggregate impact factor and journal impact factor were adopted as representative of category and journal academic performance. Linear regression was used to assess the trend of aggregate impact factor and journal impact factor. The slope (β) of the linear regression was used to represent the evolution of performance. The relationship between the 2000 EM journal impact factor and the impact factor trend of EM journals between 2000 and 2009 was measured by Pearson correlation coefficient to evaluate the evolution difference between journals with different initial impact factors.
  
  
  RESULTS
  In 2000, all 12 EM journals were published in the United States or Europe, and the language of all was English. In 2009, 10% (2/19) of the journals originated from outside North America and Europe, and 16% (3/19) were non-English-language journals. The number of EM journals increased 58% from 2000 to 2009, twice the increase in the total number of JCR-listed journals, and rank first in the rate of journal number increase among categories of clinical medicine. The impact factor of all EM journals showed an increasingly positive trend since 2000. The impact factor increased faster for high impact factor EM journals than for low-impact-factor EM journals.
  
  
  CONCLUSIONS
  An increasing number of international EM journals have appeared over the past 10 years. Every EM journal exhibited a positive impact factor trend, but the gap between EM journals' impact factors has widened in the past 10 years.
authors.affiliation: Department of Emergency Medicine, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Ching-Hsing
authors.initials: CH
authors.lastname: Lee
authors.forename: Chia-Pang
authors.initials: CP
authors.lastname: Shih
authors.forename: Yu-Che
authors.initials: YC
authors.lastname: Chang
authors.forename: Chung-Hsien
authors.initials: CH
authors.lastname: Chaou
mesh_terms: D015706:Bibliometrics; D002908:Chronic Disease; D004635:Emergency Medicine / Q000706:statistics & numerical data; D006801:Humans; D016014:Linear Models; D010506:Periodicals as Topic / Q000706:statistics & numerical data*; D014947:Wounds and Injuries