I see many sites offer a referral program for their patients stating for example, “Refer a friend to our center and receive a $25 gift card.” Is it an ethical practice?

– Study staff at research center


The use of referral incentives, sometimes referred to as “snowball sampling”, can be an effective recruiting tool, particularly with hard to reach populations. The FDA and HHS regulations for human research protections are silent with respect to the payment of incentives in research, whether those incentives are paid to study participants or researchers. However, the regulations do require that the IRB determine that informed consent is sought “only under circumstances that provide the prospective subject or the representative sufficient opportunity to consider whether or not to participate and that minimize the possibility of coercion or undue influence.” (21 CFR 50.20)  In published guidance the U.S. Food and Drug Administration (FDA) notes that “[p]aying research subjects in exchange for their participation is a common and, in general, acceptable practice”, but cautions that IRBs “should review both the amount of payment and the proposed method and timing of disbursement to assure that neither are coercive or present undue influence.” (1)

In this case, the role of the person receiving the referral is minimized because they are not directly involved in the study and prospective subjects are being referred to the site, not to a specific study. In other cases, where the referral is for a specific study, there could be a concern that patients would put significant pressure (i.e., undue influence) on their friends or even engage in threatening behaviors (i.e., coercion) to ensure their enrollment in the research so that they would receive the referral incentive.

There are some practical measures that can be put in place to minimize the chance of coercion or undue inducement occurring. U.S. Office for Human Research Protections (OHRP) FAQs suggest that “IRBs may restrict levels of financial or nonfinancial incentives for participation and should carefully review the information to be disclosed to potential subjects to ensure that the incentives and how they will be provided are clearly described.”

In the case of referral fees, IRBs may consider the structure of proposed referral plans and suggest limitations to referral plans that minimize the potential for coercion of undue inducement. Limitations might include restricting the number of referrals an individual may make, or not having the referral payment be contingent on the enrollment of the referred individuals. Many IRBs do not allow payment of referral fees to medical professionals or research staff.

Finally, the consent process should minimize the chance of coercion or undue inducement occurring. Referred individuals should understand that the choice to participate is voluntary, and the role of the individual making the referral should be minimized.


Our experts answer your research ethics and oversight questions, and share the (anonymized) answers as a resource for our industry.