Compensating research subjects is a thorny issue. Some marginalized populations may need financial support to participate and have access to potential therapeutic benefits, but researchers are warned against “undue influence” of payments in federal regulations.

While the issue of incentives raises a host of ethical issues for discussion, the problem is the dearth of data on what study participants have been compensated for all manner of studies and clinical trials.

Researchers, IRBs, and even study participants could benefit by more transparency on the issue, says Brandon Brown, PhD, MPH, a health services researcher and assistant professor in the Center for Healthy Communities at the University of California, Riverside School of Medicine. With a research focus on HIV and human papillomavirus, Brown says even outwardly transparent platforms like provide little information to inform discussions on compensating research subjects.

“So the one place where everything is transparent, at least at the onset of a study, you can’t find the incentives,” he says. “If I am going to start a study in a certain population in a certain place, how do I know what to provide participants? What I have found is there is really no guidance in terms of incentives — not in the IRB handbooks and not in the U.S. Code of Federal Regulations. Some of what I have found in the literature has really shown kind of a haphazard allocation of incentives in different contexts.”

The incentives or compensation should be in the study protocols submitted to IRBs, but the information is not posted in a central database, he notes.

“Probably the biggest concern about the lack of having this incentive information is in high-risk studies,” Brown says. “We don’t really have a good working definition of what coercion is — it has to be an excessive offer, poor judgment, and risks of harm. But it’s very difficult to agree on what is an excessive offer. People don’t really know what is being provided. There could be the same study at different sites in the U.S. and people are paid different amounts. And we don’t really know how those decisions are made on how to pay people. It could be — what I and some others think — primarily budget-driven. It could be what investigators think is fair or market forces where previous [experience suggests], ‘If we don’t pay x amount of dollars, we are not going to be able to recruit people.’”

A study1 looking at participant compensation in 207 published research articles found that only 13.5% mentioned financial compensation in any way, and only 11.1% listed amounts. Though the study was published in 2007, the lead author says that transparency about research participant compensation is still very much a current issue.

“I think that fees to study participants should definitely be transparent and available, since it can also help in understanding the study and potentially in interpreting and determining how to apply to the results to other situations,” says Robert Klitzman, MD, professor of clinical psychiatry and director of the Master of Science in Bioethics program at Columbia University in New York City.

There is a risk that payment may bias results, undermining the generalizability of a study’s findings to broader populations, Klitzman and colleagues warned in the study. In addition, offering compensation may attract subjects with less concern of the study risk.

“This information is important, since fees can affect how participants respond in studies,” Klitzman tells IRB Advisor. “I think journal articles should thus also report not only whether they have compensated participants, but how much.”

Klitzman’s study looked at compensation and incentives in research on HIV, substance abuse, depression, hypertension, and cardiac surgery. Studies on substance abusers were more likely than other studies to mention payment, suggesting that the researchers may be more sensitive to ethical concerns when working with vulnerable populations. However, overall, even studies that entailed “more than minimal risk” had low rates of reporting compensation and did not differ significantly from other studies, the researchers found.

Echoing Klitzman’s calls for research transparency, Brown advocates the establishment of an accessible database or website where incentives for various types of studies are available.

“I definitely like the idea of it being transparent, and if it is, then other people who have skills different than mine could kind of look at this as ‘Big Data’ and analyze the impact of incentives in terms of recruitment and retention and look at the mean and range of incentives in different contexts for different kinds of studies,” he says.

As a starting point, Brown is mapping out a research proposal in the area of HIV that would include the man-hours to go through records and find out what was provided in study protocols as an incentive.

“We could ask different groups who might be considered stakeholders in terms of incentive decision-making: IRBs, investigators, study coordinators, and participants themselves,” he says. “They could probably tell us a lot about what [incentive] they would need to be recruited into a study and what they would want to adhere to a protocol — to make sure that the science that was being conducted is hopefully successful.”


  1. Klitzman R, Albala I, Siragusa J, et al. The Reporting of Monetary Compensation in Research Articles. J Empir Res Hum Res Ethics 2007;2(4):61-67.