title: Application of social network analysis to health care sectors.
abstract: OBJECTIVE
  This study aimed to examine the feasibility of social network analysis as a valuable research tool for indicating a change in research topics in health care and medicine.
  
  
  METHODS
  Papers used in the analysis were collected from the PubMed database at the National Library of Medicine. After limiting the search to papers affiliated with the National Institutes of Health, 27,125 papers were selected for the analysis. From these papers, the top 100 non-duplicate and most studied Medical Subject Heading terms were extracted. NetMiner V.3 was used for analysis. Weighted degree centrality was applied to the analysis to compare the trends in the change of research topics. Changes in the core keywords were observed for the entire group and in three-year intervals.
  
  
  RESULTS
  The core keyword with the highest centrality value was "Risk Factor," followed by "Molecular Sequence Data," "Neoplasms," "Signal Transduction," "Brain," and "Amino Acid Sequence." Core keywords varied between time intervals, changing from "Molecular Sequence Data" to "Risk Factors" over time. "Risk Factors" was added as a new keyword and its social network was expanded. The slope of the keywords also varied over time: "Molecular Sequence Data," with a high centrality value, had a decreasing slope at certain intervals, whereas "SNP," with a low centrality value, had an increasing slope at certain intervals.
  
  
  CONCLUSIONS
  The social network analysis method is useful for tracking changes in research topics over time. Further research should be conducted to confirm the usefulness of this method in health care and medicine.
authors.affiliation: Department of Medical Informatics & Management, Chungbuk National University College of Medicine, Cheongju, Korea.
authors.forename: Hae Lan
authors.initials: HL
authors.lastname: Jang
authors.forename: Young Sung
authors.initials: YS
authors.lastname: Lee
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: An