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Origin and funding of the most frequently cited papers in medicine: database analysis

BMJ 2006; 332 doi: (Published 04 May 2006) Cite this as: BMJ 2006;332:1061
  1. Nikolaos A Patsopoulos, research associate1,
  2. John P A Ioannidis, professor (jioannid{at},
  3. Apostolos A Analatos, medical student2
  1. 1 Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece
  2. 2 University of Thessaly School of Medicine, Larissa, Greece
  1. Correspondence to: J P A Ioannidis
  • Accepted 2 February 2006


Objective To evaluate changes in the role of academics and the sources of funding for the medical research cited most frequently over the past decade.

Design Database analysis.

Data sources Web of Knowledge database.

Methods For each year from 1994 to 2003, articles in the domain of clinical medicine that had been cited most often by the end of 2004 were identified. Changes in authors' affiliations and funding sources were evaluated.

Results Of the 289 frequently cited articles, most had at least one author with a university (76%) or hospital (57%) affiliation, and the proportion of articles with each type of affiliation was constant over time. Government or public funding was most common (60% of articles), followed by industry (36%). The proportion of most frequently cited articles funded by industry increased over time (odds ratio 1.17 per year, P = 0.001) and was equal to the proportion funded by government or public sources by 2001. 65 of the 77 most cited randomised controlled trials received funding from industry, and the proportion increased significantly over time (odds ratio 1.59 per year, P = 0.003). 18 of the 32 most cited trials published after 1999 were funded by industry alone.

Conclusion Academic affiliations remain prominent among the authors of the most frequently cited medical research. Such research is increasingly funded by industry, often exclusively so. Academics may be losing control of the clinical research agenda.


  • Embedded Image An appendix with the 289 most frequently cited articles is on

    NAP and AAA thank A Germenis for his encouragement. This work was conducted under the auspices of the International Campaign to Revitalise Academic Medicine (ICRAM) as part of the effort to evaluate the evidence base for academic medicine. Members of the ICRAM Working Party are listed on

  • Contributors JPAI had the original idea for the study and also wrote the protocol, which was commented on by the other two authors. NAP and AAA performed the data extraction and discrepancies were resolved by JPAI. NAP and JPAI performed the statistical analyses. All authors interpreted the results. JPAI and NAP wrote the final manuscript and AAA commented on it. All authors approved the final version. JPAI is guarantor.

  • Funding None.

  • Competing interests None declared.

  • Ethical approval Not required.

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