Some reveal that they are getting funding, but others keep hidden who their sponsors are, researchers from the University of Pennsylvania discovered when they lifted the lid on 104 patient groups.
Around 80 per cent were open about their drug company funding, but the rest hadn't revealed their pharmaceutical connections. Just one of the 104 groups analysed didn't get any funding from the industry.
The funding creates a conflict of interest because many of the groups advocate the use of specific drugs, or lobby regulators to get a new drug approved while all the time maintaining it is for the benefit of patients.
The researchers say it is time to introduce a new 'sunshine law' where drug companies are forced to reveal all the donations they make. This level of transparency is essential so that patients, researchers and regulators can temper any advice or advocacy from the groups.
The groups who were reviewed were each receiving $7.5m or more in donations, and 23 were being given $1 million or more each year from the pharmaceutical industry.