Many medical journal editors are put under pressure to alter editorial content by the associations that employ them, a survey has found.
The authors of the study warn that whenever editorial freedom is compromised, it calls into question the integrity of the research published in the journal.
If the publication was a leader in its field, the stain could spread to an entire scientific discipline, researchers said.
Ronald Davis, director of the Center for Health Promotion and Disease Prevention in Detroit, in the US, and Marcus Mullner, a researcher at the University of Vienna Medical School, Austria, questioned the editors of 33 medical journals owned by not-for-profit organisations.
The research, published in the journal Science and Engineering Ethics , found that 70 per cent of editors reported having complete editorial freedom. The remainder claimed a high level of independence.
But a substantial minority said they had been put under pressure in recent years over editorial comment.
Forty-two per cent reported that their parent association's leadership had attempted to influence the editor's judgement.
Dr Davis said: "I think our study shows that there is a potential danger out there, a pressure that can compromise editorial freedom."
He said that although the perceived level of independence was unexpectedly high, many editors might yet experience attempts to interfere with their work.
"If editors have not delved into an area of controversy, they might not have tested the extent to which they have editorial freedom," Dr Davis said.
The researchers note that two-fifths of the journals in the study did not have an explicit written policy on editorial independence. They say that this is an essential first step that could be followed by safeguards designed to insulate the editors from pressure.