Research studies funded by drug companies have risen by 43 percent in the last decade, while US government-funded studies have dropped 27 percent, US scientists said Tuesday.
Budgetary pressures may have played a role in the decline of purely academic research studies, said the findings in the Journal of the American Medical Association (JAMA).
This year's National Institutes of Health (NIH) -- the largest government funding source for research -- $30.4 billion budget was 14 percent less than a decade ago when adjusted for inflation, the study authors said.
"My concern is that independent trials are on the decline and that means we have less high-quality data to inform public health that are not influenced by commercial interests," said lead researcher Stephan Ehrhardt, a doctor and associate professor at Johns Hopkins University.
"When I am doing a government-funded trial comparing two treatments, I start with the assumption that both treatments are equal. I don't have a vested financial interest in the outcome," he added.
"But when I am a drug company testing my new product, my objectivity can be compromised by the company's bottom line since it costs me millions of dollars to develop and test my product to get it on the market. It might be difficult for me to be completely objective. The stakes are very high."
Knowing that belt-tightening has limited the growth of the NIH budget, Ehrhardt and colleagues hypothesized that commercially funded research might be on the rise.
Looking specifically at clinical trials that use intervention therapies meant to study the benefits and harms of different treatments for human illnesses, they found that commercial ventures run six times more trials than academic investigators.
The number of newly registered industry-sponsored trials increased 43 percent over the time period from 4,585 in 2006 to 6,550 in 2014, said the research letter in JAMA, which was based on data from ClinicalTrials.gov.
The number of newly registered NIH-funded trials decreased 24 percent over the same period from 1,376 in 2006 to 1,048 in 2014, it added.
Clinical trials may compare a new therapy to a conventional one, or look at the effectiveness of a medication versus a placebo.
Pharmaceutical companies typically fund studies that test their own products.
In addition to flat funding for NIH, there is growing competition for limited research dollars from new research areas like genomic research and personalized medicine.
"We need a discussion on how to best allocate our health-related research budgets," said Ehrhardt.