Cash in hand is a more potent incentive to participate in clinical research than any perception of investigator impartiality – or at least for students, a US study suggests.

The issue of when clinical investigators’ financial interests in the outcome of a trial, or their financial ties with the trial sponsor, should be disclosed to potential study participants or the wider public has aroused “considerable discussion”, notes the Food and Drug Law Institute, which published the new research in the latest issue of its Food and Drug Law Journal. Less attention has been paid, though, to the actual impact of these disclosures on potential trial subjects.

This element was addressed in a study by Dr Gregory Guagnano, associate professor of sociology and anthropology at George Mason University (GMU) in Virginia, and Jeffrey Gibbs of the law firm Hyman, Phelps & McNamara. They asked 297 undergraduate students at GMU how likely they would be to agree to participate in a clinical trial of a dietary supplement with potential to improve memory.

Each student was told that the clinical investigator had one of three levels of financial interest, namely: the investigator was an employee of the company whose product was under evaluation; was an employee and consultant of that company; or was an employee and patent holder.

The outcome was that willingness to participate in the study was not affected by the degree of conflict-of-interest disclosure. The researchers did find that students who rated the investigator as more trustworthy were more likely to agree to participate. However, the assessment of trustworthiness was not influenced by the extent of the investigator’s financial stake in the trial.

Offering the students money did have a marked impact on their willingness to participate. Students who were told they would receive US$20 were significantly more likely to want to take part in the trial than those who were offered no money.

'Limited' impact?
The study results suggest that “learning about an investigator’s financial stake may have a relatively limited impact on deciding whether to participate”, Dr Guagnano commented. “If replicated, these findings could affect the way in which clinical study disclosure requirements are established and implemented.”

Gibbs added: “There are a number of reasons to mandate disclosures, but this study suggests that disclosure of conflicts may not play a large role in decision-making. Given that some courts have reached decisions based on their believing that knowledge of a financial stake would actually change people's behavior, this study shows that courts need to rely on facts, not assumptions.”