Most members of US panels that define conditions such as high blood pressure and dementia have financial links to drug companies, according to a new Australian study.
Bond University researchers raise questions about processes used for defining diseases and say about 75 per cent of members of US panels have declared conflicts of interest.
The study, under the direction of Professor Paul Glasziou, is part of wider research on over-diagnosis, where patients with mild symptoms or at low risk may be labelled as ill and receive treatments that may do them more harm than good.
"There is a clear conflict of interest," says lead author Ray Moynihan, a senior research fellow at the university.
"If a panel of experts decides to expand the definition of a condition, then that is widening the market for the companies those experts are working with."
He says US panels are influential globally, including in Australia.
"We are talking about common conditions like high blood pressure, high cholesterol, asthma and depression."
One example is a 2003 panel that created a new diagnostic category called pre-hypertension or pre-high blood pressure.
"That instantly created a very large number of people who fitted into that category. A large proportion of members of the panel had extensive ties to companies that manufacture drugs for high blood pressure."
Mr Moynihan says the paper published in the journal PLOS Medicine does not make any judgments about the decisions of individual panels.
However, the authors hope it will provoke debate about whether the process of disease definition might need to be reformed.