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

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.