Major pharmaceutical companies injected more than $34m into patient advocacy groups in four years, often at the same time as they lobbied for related drugs to be listed on the pharmaceutical benefits scheme, new research suggests.

A study published by University of Sydney’s Charles Perkins Centre on Wednesday has for the first time mapped the links between big pharmaceutical players and consumer health groups in Australia.

It shows 34 pharmaceutical companies made 1,482 sponsorships worth $34.5m to 230 consumer health organisations between January 2013 and December 2016. The sponsorships were on average worth $23,206.33 and came in the form of direct donations, in-kind support, or product donations.

The largest amount of money was sent to groups representing cancer, eye health and nervous system disorder patients, according to the paper, which will be published in the International Journal of Health Services.

In most cases, the consumer groups receiving the largest amounts of money were sponsored by pharmaceutical companies that had related drugs “under review for public reimbursement” through the PBS, which the industry often relies on to turn a profit.

The research does not establish that the consumer health groups had directly advocated for their sponsors’ drugs to be PBS listed. But it did find a “potential correlation between a company’s commercial interests and its sponsorship of consumer groups that operate in that same disease area”.

“In most cases, the main funders of the top five consumer groups in our analysis were companies that at that time had drugs under review for PBS listing,” the paper found. “In many cases, these drugs were initially rejected and then later approved for reimbursement.”

The research cited the example of the Macular Disease Foundation Australia, which received the largest amount of pharmaceutical sponsorship during the four-year period. Its top pharmaceutical sponsor was the multinational giant Bayer, a company that markets the macular degeneration drug aflibercept.

Aflibercept was initially PBS listed for age-related macular degeneration but Bayer wanted an extended listing to cover additional patients. It is impossible to tell whether consumer groups sponsored by Bayer made submissions directly in support of an extended PBS listing, because the documents are not public.

“Public access to this information would allow analyses of potential associations between industry funding and positions of consumer organisations,” the researchers said.

The Macular Disease Foundation Australia denied any suggestion that receiving pharmaceutical funding posed a conflict of interest in its role advocating for those with macular disease. Its chief executive, Dee Hopkins, said the foundation received funding from a variety of sources – including donations and bequests, government and sponsorship – which were openly disclosed and used for representation, education, research, awareness and support services.

“Since its inception, MDFA has always operated with integrity and transparency and we do not see a conflict of interest in the receipt of funds from any of our sponsors,” she said. “As the national peak body, we pride ourselves on our independence.”

Hopkins said the MDFA typially made representations to the pharmaceutical benefits advisory committee (PBAC) whenever any new macular disease drug is available for treatment.

“MDFA’s medical committee, which consists of Australian ophthalmologists who are respected authorities on macular disease, provides oversight and input to submissions made to the PBAC,” she said. “All submissions require full transparency and disclosure of funding.”

The research identified the top 10 biggest recipients of pharmaceutical sponsorship as Macular Disease Foundation Australia, Lung Foundation Australia, MS Australia, Arthritis Australia, Rare Cancers Australia, Leukaemia Foundation, Hepatitis Australia, Myeloma Australia, Kidney Health Australia, and Crohn’s & Colitis Australia.

Ten of the 34 biggest sponsors donated some $23,485,081, or 68.1% of the total. The largest sponsors included Bayer, Novartis, Janssen, Pfizer, Sanofi, Amgen and Boehringer.

“Our analysis has documented widespread interactions between the pharmaceutical industry and health consumer organisations in Australia over the four-year study period,’” the paper said. “This raises concerns about potential commercial influence on the activities of health consumer organisations. Considering the important role that consumer groups play in education, advocacy and health policy, strategies to prevent undue influence from corporate donors are urgently needed.”

University of Sydney and Charles Perkins Centre academic Barbara Mintzes, who led the study, said concerns about pharmaceutical influence of consumer health groups could be addressed by additional transparency measures or by reducing the reliance of consumer health groups on pharmaceutical sponsorship.

“I would say that a solution would be public funding of the groups,” she told Guardian Australia. “Either public funding, or if the industry has an interest in philanthropy, to manage that in a way where there is independently managed fund, like a blind trust.”

A Bayer spokeswoman said the company was proud to support consumer groups and “recognises the important role they play in advocating on behalf of patients thereby enhancing the quality use of medicines”.

“We believe that the patient perspective on medical conditions and their management is a vital component for industry in the development and delivery of medicines,” she said. “HCOs ensure the patient voice is heard and provide valuable insights to make sure the Industry addresses patient needs.”

She said Bayer was fully transparent in its relationship with health consumer groups through its involvement with Medicines Australia.