February 24, 2024

When research participation pays, some people lie

Even small sums make a difference

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Offering compensation can be an important tactic to attract potential participants for enrolment in research studies, but it may come at a cost. A new study from the Perelman School of Medicine at the University of Pennsylvania found that up to 23% of respondents lied about their eligibility to participate in a survey when they were offered payment, even small amounts.

Anecdotal evidence and common sense suggest that offering money may encourage participants to lie about their eligibility or other aspects of study participation in order to secure payment. But few studies have investigated this intuition. The new findings, published in JAMA Network Open, suggest the practice may be pervasive.

A total of 2,275 respondents participated in a nationally representative, randomized survey on flu vaccination status. One study group lacked motivation to lie about whether they had recently had a flu shot because their eligibility didn't depend on it. Their reported rates of flu vaccination were therefore used to determine the true rate of vaccination in the study population. Other groups were offered $5, $10, or $20 for participation and were told they were eligible only if they had (or in some groups, had not) received a recent flu shot. If no one was lying, all study groups would have reported about the same rates of flu vaccination.

“Instead, we found evidence of significant deception by participants who were not eligible, but claimed they were in order to be able to join the study,” said first author Holly Fernandez Lynch. “This type of behaviour not only undermines a study's integrity and its results, but in a study with eligibility criteria that are intended to protect participants, it also has the potential to put participants at risk.”

One of the study's most interesting findings is that more money wasn't associated with higher rates of deception. “This suggests that keeping payments low will not necessarily prevent deception,” said study co-author Steven Joffe. “It also suggests that higher payments may encourage recruitment without posing a greater risk to the study's integrity.”  

Michael Cook is editor of BioEdge

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