title: The importance of national and international collaboration in adult congenital heart disease: A network analysis of research output.
abstract: BACKGROUND
  The determinants of adult congenital heart disease (ACHD) research output are only partially understood. The heterogeneity of ACHD naturally calls for collaborative work; however, limited information exists on the impact of collaboration on academic performance. We aimed to examine the global topology of ACHD research, distribution of research collaboration and its association with cumulative research output.
  
  
  RESULTS
  Based on publications presenting original research between 2005 and 2011, a network analysis was performed quantifying centrality measures and key players in the field of ACHD. In addition, network maps were produced to illustrate the global distribution and interconnected nature of ACHD research. The proportion of collaborative research was 35.6 % overall, with a wide variation between countries (7.1 to 62.8%). The degree of research collaboration, as well as measures of network centrality (betweenness and degree centrality), were statistically associated with cumulative research output independently of national wealth and available workforce. The global ACHD research network was found to be scale-free with a small number of central hubs and a relatively large number of peripheral nodes. In addition, we could identify potentially influential hubs based on cluster analysis and measures of centrality/key player analysis.
  
  
  CONCLUSIONS
  Using network analysis methods the current study illustrates the complex and global structures of ACHD research. It suggests that collaboration between research institutions is associated with higher academic output. As a consequence national and international collaboration in ACHD research should be encouraged and the creation of an adequate supporting infrastructure should be further promoted.
authors.affiliation: Division of Adult Congenital and Valvular Heart Disease, Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany.
authors.forename: Melanie Iris
authors.initials: MI
authors.lastname: Orwat
authors.affiliation: Imperial College of Science and Medicine, London, UK; Adult Congenital Heart Centre and Centre for Pulmonary Hypertension, NIHR Cardiovascular and Respiratory Biomedical Research Unit, Royal Brompton Hospital, London, UK.
authors.forename: Aleksander
authors.initials: A
authors.lastname: Kempny
authors.affiliation: National Register for Congenital Heart Defects, Berlin, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Bauer
authors.affiliation: Imperial College of Science and Medicine, London, UK; Adult Congenital Heart Centre and Centre for Pulmonary Hypertension, NIHR Cardiovascular and Respiratory Biomedical Research Unit, Royal Brompton Hospital, London, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gatzoulis
authors.affiliation: Division of Adult Congenital and Valvular Heart Disease, Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Baumgartner
authors.affiliation: Division of Adult Congenital and Valvular Heart Disease, Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany; Imperial College of Science and Medicine, London, UK; Adult Congenital Heart Centre and Centre for Pulmonary Hypertension, NIHR Cardiovascular and Respiratory Biomedical Research Unit, Royal Brompton Hospital, London, UK. Electronic address: gerhard.diller@ukmuenster.de.
authors.forename: Gerhard-Paul
authors.initials: GP
authors.lastname: Diller
mesh_terms: D000328:Adult; D035843:Biomedical Research / Q000458:organization & administration*; D019468:Disease Management; D014943:Global Health; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000628:therapy; D006801:Humans; D007255:Information Services / Q000458:organization & administration / Q000706:statistics & numerical data; D007391:International Cooperation; D017063:Outcome Assessment, Health Care; D012106:Research / Q000458:organization & administration / Q000706:statistics & numerical data; D013597:Systems Analysis
keywords: Adult congenital heart disease; Bibliometric analysis; Network analysis; Research output