The Ethics of Clinical Trial Payments (and Non Payments)

In February 2025, WCG and Mural Health held a joint webinar aimed at tackling ambiguity and open questions about what is allowed and recommended in paying clinical research participants. Sam Whitaker, CEO of Mural Health, and Kelly FitzGerald, IRB Executive Chair and VP IBC Affairs at WCG, shared their insights and answered audience questions in real-time.

Due to an overwhelming amount of questions shared before and during the session, we realized there is a need to provide the industry with a deeper understanding of the rationale behind different aspects of trial payments, and arm decision makers with tactical guidelines to put into place and use to educate their organizations.

This blog is the first in a series exploring key aspects of participant compensation, including payment types and amounts, tax implications, and methods of disbursement. We’re starting with the foundation: the ethics of clinical trial payments.

Ethics in Participant Payments - Key Principals

When it comes to participant payments in clinical trials, ethics aren’t just a consideration, they’re the foundation. Thoughtful, transparent compensation practices help ensure that clinical trials are inclusive, accessible, and respectful of the people who make them possible. Making participants whole by reimbursing expenses or paying a reasonable rate is not only allowed by IRBs - it is encouraged. Before we get into the nuances of type of participant payments, it’s important to address the terms commonly used in reference to the ethics of participant payments:

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• Coercion: Largely irrelevant in trials. Coercion would indicate threats of harm, which are not applicable for trial participant payments. Instead, focus should be directed to Undue Influence.
• Undue influence: Using money, incentives or persuasion to influence participants to overlook the risks of the research in making their decision to participate. While certain payment structures or amounts could be unduly influential, covering the trial related and reasonable expenses of participants is not considered undue influence. As we’ll explain below, undue influence would only come into play after participants are made whole for their reasonable expenses and compensated for their time.

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Beyond considering the ethics of payments, we must also note that not all payments are the same. At the highest level, there are three primary types of payments:

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• Reimbursements: Covering specific out-of-pocket expenses, such as a taxi, a flight, a meal, lodging or any other trial expenses.
• Compensation: Covering time, effort, inconvenience, missed work, etc.
• Stipends: A flat amount for all expenses. Includes time and effort, childcare, and compensation for study specific activities.

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With this framework in mind, we are going to address frequently asked ethical questions about participant payments.

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A Deeper Dive - Q&A

From an IRB perspective, what ethical considerations should be taken into account regarding participant payments to avoid undue influence while maintaining fairness?

To ensure ethical compensation without undue influence, it’s critical to separate reimbursement from compensation. Reimbursing participants for out-of-pocket expenses, whether for a taxi, a flight, a meal, or any other trial-related expense, is about making them whole, and therefore does not constitute undue influence.

Compensation for time and burden should be considered separately, using a general benchmark for compensation across participants (such as fixed local minimum wage), and then adjusted based on the complexity of the study.

While stipends are common for the ease of site administration, best practice provides full reimbursement first, then compensation based on the participant’s effort. This is due to the incompatibility between the stipend’s fixed amount and an individual’s actual expense, as well as the negative tax implication of stipends (more on this in our following blogs).

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How do you quantify participant burden beyond compensation for time?

It is true that aspects such as emotional and physical burden are harder to quantify than time. While compensating for time may not fully compensate the individual, it is a good starting point after fully reimbursing participants for their expenses.

To determine amounts associated with time, use a logical and objective rationale (e.g. - based on the median household income of a country, or metro area as a basis). It is important to remember that a payment associated with time/effort is not a replacement for expense reimbursement. It should be a payment provided only after all reasonable expenses have been reimbursed.

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From an ethics perspective, is there a cap on how much compensation can be given as reimbursement?  Does the IRB regulate this or is it strictly up to the Sponsor, CRO or SMO?

There is not a regulatory cap or an ethical cap on compensation. As we mentioned, the guiding principle for compensation should be making the participant financially whole, so that trial participation is as financially neutral as possible. To accomplish this, participant budgets should be built from the bottom up to consider the potential expenses that may be incurred by the participant, and the time and effort involved in the study. We also suggest providing IRBs with the payments rationale. 

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Is it unethical to not offer stipends in placebo-controlled trials?

While a trial can still meet ethical standards without offering stipends, compensating participants fairly for their time and effort is widely recognized as best practice. Placebo-controlled trials are a great example of when making participants financially whole is especially important, but fair payments should be the norm across all trials.

As mentioned above, stipends should be used only after expense reimbursement has been provided. If no financial support is being provided, the absence of financial support may be exploitative.

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What if a site declines to offer stipends or reimbursements due to administrative burden? 

While administrative burden is a valid concern for research sites, not providing any financial support completely shifts that burden to participants, and could be considered exploitative. 

We encourage you to educate the sites you work with on the importance of participant compensation, and to  leverage solutions that streamline payment processes to ease the burden of managing payments.

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Is paying participants quarterly considered undue influence compared to per-visit payments?

This could be acceptable for studies that require this payment structure. We recommend providing a rationale for this structure when submitting the study for IRB approval. 

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Should participant payments reflect the local cost of living?

Yes, participant payments should account for differences in local cost of living. 

What’s considered fair compensation in one region may fall short in another, so adjusting payments based on geography can support more equitable participation. While this approach used to introduce complexity for sites and sponsors, today’s technology makes it possible to implement location-based payment strategies efficiently—without adding administrative burden.

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Conclusion

Your webinar questions highlight just how nuanced and essential ethical considerations around clinical trial payments truly are, touching on fairness, transparency, and the need to avoid both undue influence and potential exploitation.

If you’d like to stay in the loop on future blogs, including closer looks at participant payment types, tax implications and differences in disbursement, sign up for our newsletter. Also feel free to reach out with any additional questions or comments.