Participants’ Perspectives on Incentives for Research Participation: A Qualitative Study

Abstract

Investigators commonly offer incentive payments to research participants to promote recruitment and retention. Yet, the ethics of offering payment to research participants continues to be debated. Prior conceptual work has addressed some of these concerns; there is, however, also a need for empirical evidence to understand the effects of payment on participants. Here, we report the results of a qualitative study comprising (1) discourse analysis of recruitment conversations between study coordinators and potential participants for an actual clinical trial, and (2) semi-structured interviews with participants addressing the effects of the incentive on their decision-making. Many participants reported that money had been a motivation for enrolling in the clinical trial, but did not use reasoning that suggested undue influence, unjust inducement, or therapeutic misconception. These findings add to a growing body of literature suggesting that payment is an ethically acceptable tool for promoting recruitment and retention in clinical trials.

Introduction

Difficulty enrolling participants in randomized clinical trials (RCTs) is a recognized barrier to evaluating health interventions.¹ To overcome this barrier, many investigators offer payment to participants. Though widespread, this practice remains ethically contentious.² It has largely been debated on conceptual grounds, and concerns include that payment might unduly influence or coerce participants, undermining their informed consent, or result in the disproportionate enrollment of low-income or otherwise disenfranchised individuals.³

Prior studies have assessed how offers of payment affect willingness to participate in hypothetical RCTs.⁴ By contrast, the recently published Randomized Evaluation of Trial Acceptance by INcentive (RETAIN) study tested the extent to which incentives improve recruitment or exert unintended influences on patients’ decisions to enroll in actual RCTs.⁵ As a complement to RETAIN’s quantitative analyses, we conducted a qualitative study to explore participants’ own experiences and perspectives in greater detail.

Here, we report the results of that qualitative study, which included two components: discourse analysis of recruitment conversations between the study coordinator and potential participants and semi-structured interviews with participants.

Methods

RETAIN has been described in detail elsewhere.⁶ In brief, 2 RCTs of incentives were embedded in 2 parent RCTs—one evaluating an ambulation intervention (NCT03321279) and one comparing smoking cessation interventions (NCT02378714). RETAIN was approved by the University of Pennsylvania Institutional Review Board (IRB) using a waiver of informed consent. Here, we report the results of a qualitative study that was embedded into the ambulation trial only. Participants in the ambulation trial were given a wearable device which tracks daily step counts and sleep to measure the impact of gamification on physical activity.⁷

Eligibility

Participants eligible for this qualitative study were those approached for informed consent to participate in the ambulation trial as part of RETAIN. Embedded RETAIN recruitment for this qualitative study occurred from February 8, 2019 through May 31, 2019. Research coordinators conducted in-person recruitment for the ambulation trial in patients’ hospital rooms.

Randomization

Potential participants for the ambulation trial were randomized in equal proportions (33.3%) to one of three incentive groups: $0, $100, or $300. Because RETAIN was conducted with a waiver of informed consent, potential participants in the ambulation trial were only aware of the incentive to which they had been randomized; the research coordinator was unmasked to the incentive information. The research coordinator adhered to an IRB-approved verbal communication script during the recruitment discussion. The assigned incentive was also included in the parent trial’s informed consent documents.

After RETAIN outcomes were collected, participants were debriefed using an IRB-approved script that explained the rationales for assigning different incentives and not informing the participants about RETAIN. All participants, regardless of the initially assigned incentive, ultimately received the maximum incentive (i.e., $300).

Data Collection and Analysis

This qualitative study had two components: (1) a discourse analysis of the in-person recruitment discussions between the research coordinator and prospective participants up to the point at which a decision was made to decline or enroll in the ambulation trial; (2) after participation in RETAIN was complete and the participant had been debriefed, semi-structured interviews with participants about their decision to participate in the ambulation trial.

Recruitment discussions between the study coordinator and potential participants were audio recorded, professionally transcribed—including tonal details from speakers such as word emphasis, intonations, laughter, pauses, and interruptions, and thematically analyzed in accordance with modified grounded theory framework using NVivo 12.⁸ Three team members (EL, FB, JM) met iteratively to review transcripts as data were collected, define themes to develop codes to characterize the recruitment discussion, and check for data saturation.

For the second qualitative component, semi-structured interview guides were developed by the multi-disciplinary research team following a review of literature. Telephonic interviews were generally conducted within 2 weeks of the in-person recruitment discussion (78%) by one interviewer (JM); 5 interviews were conducted later, up to 62 days following the recruitment discussion. All interviews were recorded (though one was lost due to a faulty recorder), professionally transcribed, de-identified, and thematically analyzed in accordance with modified grounded theory framework using NVivo 12.⁹ Three team members (EL, FB, JM) met iteratively to review transcripts, identify salient themes to develop the codebook, and check for data saturation.

The codebook organized responses into defined categories to code content, track themes, and generate result summaries. Three team members coded the transcripts from the recruitment conversations (CB, WE) and the semi-structured interviews (CB, JM); one reviewer (CB) coded all data, others served as double-coder. The reviewers used the interrater reliability function in NVivo to ascertain agreement among coders.

Human Subjects Protections

The University of Pennsylvania IRB approved this qualitative study. Participants gave verbal consent for audio recording of the recruitment discussion and semi-structured interview.

Results

Eighty-six individuals were invited to participate in this qualitative study; of those, thirty-eight agreed to have their recruitment discussions audio recorded for discourse analysis. Of the 37 individuals included in the discourse analysis, 36 were recruited into the ambulation trial; of the 36, 24 completed the 30-minute semi-structured telephonic interview. One interview was lost due to a faulty recorder, resulting in an analysis of semi-structured interviews for 23 individuals. See Table 1 for participant characteristics.

Table 1.

Participant Demographics

	Discourse Analysis (N=37)	Semi-Structured Interview (N=23)
Age (years)
Mean (SD)	39.2 (13.1)	38.7 (12.4)
Median [Min, Max]	40.0 [19.0, 65.0]	39.0 [21.0, 65.0]
Sex
Male	11 (29.7%)	5 (21.7%)
Female	26 (70.3%)	18 (78.3%)
Race
Black/African American	13 (35.1%)	9 (39.1%)
White	18 (48.6%)	11 (47.8%)
More than one race	1 (2.7%)	0 (0%)
Other	5 (13.5%)	3 (13.0%)
Missing	0 (0%)	0 (0%)
Financial Incentive
$0	10 (27.0%)	8 (34.8%)
$100	13 (35.1%)	7 (30.4%)
$300	14 (37.8%)	8 (34.8%)
Marital Status
Married or living with partner	14 (37.8%)	9 (39.1%)
Never married	17 (45.9%)	10 (43.5%)
Other	6 (16.2%)	4 (17.4%)
Missing	0 (0%)	0 (0%)
Education
Some high school	1 (2.7%)	0 (0%)
High school graduate	12 (32.4%)	7 (30.4%)
Some college	9 (24.3%)	7 (30.4%)
College degree	15 (40.5%)	9 (39.1%)
Missing	0 (0%)	0 (0%)
Household Income
<$10k	3 (8.1%)	2 (8.7%)
$10-$19k	5 (13.5%)	4 (17.4%)
$20-$29k	4 (10.8%)	1 (4.3%)
$30-$49k	5 (13.5%)	4 (17.4%)
$50-$99k	9 (24.3%)	6 (26.1%)
$100k+	10 (27.0%)	6 (26.1%)
Missing	1 (2.7%)	0 (0%)
Personal financial well being
Mean (SD)	6.01 (2.67)	6.21 (2.57)
Median [Min, Max]	5.63 [1.00, 10.0]	5.63 [1.00, 10.0]
Prior research experience was good?
Generally good prior research experience	14 (37.8%)	8 (34.8%)
No good prior research experience	23 (62.2%)	15 (65.2%)
Missing	0 (0%)	0 (0%)
Research Attitudes Questionnaire
Mean (SD)	27.1 (3.01)	27.9 (2.78)
Median [Min, Max]	27.0 [18.0, 35.0]	28.0 [23.0, 35.0]

Recruitment Discussions

Recruitment discussions were generally one-sided, with the research coordinator doing the majority of talking and closely following the IRB-approved verbal communication script. During the recruitment discussion, and depending on which incentive group the participant had been randomized to, the research coordinator would tell the patient that they would or would not be paid for participating—and if they would be paid, how much.

Only a handful of participants audibly reacted to the financial incentive. For example, a participant randomized to the $100 arm was asked by the research coordinator, “Are you interested?” The participant said “sure” and then somewhat abruptly exclaimed, “A hundred bucks!” Upon hearing that she would receive $100 if she enrolled in the ambulation trial, another participant said, “Wow, that is fantastic! I was interested anyway.”

Less than half (16 of 37) of participants asked questions during the recruitment discussion, and many of these questions focused on risks and burdens of participation in the ambulation trial. Participants asked: about the time commitment or study duration (7 participants); if their current health or mobility status would be appropriate for the study (4); what the wearable activity tracker monitored or if they could use their existing smartwatch (3); when the financial incentive would be paid (3); or about data privacy and security (2).

Knowledge of Research

Research was not consistently mentioned in the initial recruitment discussion, reflecting the nature of the IRB-approved verbal communication script used by the research coordinator. For most participants, the recruiter discussed the ambulation trial as a “program” for which the patient was eligible. Explicit mentions of “research” or “study” by the recruiter occurred in 10 of 37 discussions. Only one participant used such language during the recruitment discussion. However, in the subsequent semi-structured interviews, most participants (21 of 23) described the ambulation trial as research or expressed an understanding that their data were being used for research purposes.

Incentive Was Not Important

At the time of the semi-structured interview, slightly more than half (13 of 23) of the participants indicated that financial incentive was not important to their decision to participate in the ambulation trial. Eight of these had been randomized into the $0 incentive arm, while five were initially offered a $100 or $300 incentive.

One participant in the $0 arm who self-identified as “a pretty independent single mom” hypothesized:

I would have felt almost embarrassed or pressured into doing it [participating in the ambulation trial]…pressured or embarrassed if I had [known] up front, like, you’re going to get some money for participating. I still would have participated, but yeah, I wouldn’t have felt good about it. … [I]t would have felt almost like I was being bribed. You know what I mean?

Individuals who denied “participating for the money” noted that it was “cool” or “nice to get” the incentive, but not “my deciding factor.” In fact, one participant volunteered during the interview that while “I’m not rich, and I wouldn’t turn it [the incentive] down,” she had agreed to “participate [in the ambulation trial] even before she [the research coordinator] told me there was money involved.”

Participants who indicated the incentive was not important to their decision making expressed a greater familiarity with research and the research process than did those who indicated the incentive was important to their decision making. Some were familiar with research because they had previously been recruited for studies, while others worked at an institution that conducted research.

Additionally, participants in this group mentioned potential social benefits of research more frequently than did participants who described the incentive as an important factor in their decision making. For instance, a participant randomized into the $0 arm explained that because part of her job as a nurse “is getting people up and moving” the ambulation trial might benefit “my field.” A participant who was randomized into the $300 arm, explained:

I’ve been friends with people that are researchers, and I know how much they need the information that they need. That’s mostly why I got involved with [the ambulation trial] to start with, just to provide what they needed to try and get the research done, so that they could help others.

This was echoed by a participant who reported, “Honestly, … I always say ‘yes’ to a study if I can because you need subjects for a study to work.”

Incentive Was Important

Ten participants said that the incentive was an important factor in their decision to participate in the ambulation trial. These participants were clear that while money was a source of motivation for them, it was not the only source. Additional sources of motivation included the potential for experiencing personal health benefits, receiving a wearable activity tracker, or advancing science. Asked about reasons for participating in the ambulation trial, one individual explained, “The money for one thing, and two, because I thought it [the ambulation trial] could help me. Help my physical well-being.” Another explained that the wearable activity tracker—which all participants in the ambulation trial received to track their step counts—was “more effective for me … than the payment … but the payment was definitely a huge incentive.” Still others noted that they were motivated by the financial incentive but also wanted to help others or “gain some knowledge” through their participation in the ambulation trial.

In discussing the role of the incentive in their decision making, several individuals reflected on their personal finances. One participant who described herself as “low income … on a fixed income … always looking for a way to get or save money” stated that the $100 financial incentive was “important” but went on to say the incentive “wasn’t the actual main reason. I was very interested to see what kind of information I would get from it [the ambulation trial] and if it would help me.” Another participant asserted that the incentive “helped me with my financial problems” but that “I wanted to also get into it [the ambulation trial] because it was interesting.” Later in the interview, this same participant stated that she was “uneasy about the tax [consequences of receiving the $300]…[b]ecause I am on SSI [Supplemental Security Income].”

Several participants reported that they would not have participated in the ambulation trial had they been offered a lower financial incentive or no financial incentive. One elaborated and said that while some of the potential benefits of participation like “helping research” were “abstract,” the $100 financial incentive was “something very concrete, and for me I think that was definitely important in my decision to participate.”

Perceptions of Study Risks and Burdens

Whether they described the incentive as being important to their decision making or not, participants “didn’t really perceive any risks in participating” and viewed the ambulation trial as “low effort” or “easy enough.” Though some cited a privacy breach as a potential risk, most expressed comfort with data sharing. Asked directly, participants denied that they money made them think differently about the ambulation trial’s risks and burdens. “[I]t didn’t affect my judgment,” one asserted.

Participants felt that the benefits of participation in the ambulation trial—identified by them as the “amazing” financial incentive, “super nice watch,” or direct health benefits of getting “my butt in gear”—compared quite favorably to the risks and burdens of participation. A typical response came from a participant in the $100 arm who asked, “Who would not want to receive money from just walking around? I mean that’s something that I should be doing every day anyway, so why not?”

A few participants noted that the incentive had initially given them pause or raised concerns that the research was riskier or more burdensome than it actually was. One participant explained that, upon hearing that she would receive the wearable activity tracker and also $300 for participating in the ambulation trial, “It just seemed like it was like too good to be true.” However, she was reassured after talking with the research coordinator:

Once she [the research coordinator] explained this to me, I was like, “Sure.” Then, it sounds easy. I said I don’t mind participating. I just thought it was gonna be a lot more involved than – like I said, sometimes, things … are too good to be true.

In the semi-structured interviews, several participants described research-related risks or burdens that would have made them hesitant or even unwilling to participate in the ambulation trial; these included, taking an investigational drug, undergoing muscle biopsies, or needing to make frequent clinic visits. Some observed that money does not always suffice to overcome risks and burdens. For example, one participant detailed a prior experience of being recruited for a study “with hyperbaric chambers” in which the researchers wanted “to give you the bends.” At three separate times she asserted, “[T]hey could have offered me $1,000,000 to do that [hyperbaric medicine study], and I wouldn’t have done it.”

Incentives as a General Tool for Recruitment and Retention

Participants described incentives as a tool for improving recruitment. Some reasoned that the incentive could help “you recruit faster” as well as make the sample more diverse. One participant suggested that incentives might be more appealing to worse-off individuals.

Because it depends on what income level you’re at. Who you’re approaching, it does give them some type of incentive for the people that compete in the study that may be of lower income. … [F]or me, it wasn’t the deciding factor, that’s all I’m saying. It’s great that you get an additional $300, but it wasn’t just the deciding factor for me. But it would probably help someone who is of lower means.

Some participants worried that while an incentive could generate initial interest in research, individuals might subsequently drop out because they were not intrinsically motivated or had not joined the trial for the “right reasons,” such as a desire to help others or to “find out stuff.” One individual cautioned, “[P]eople should be really grateful that they did get [a] financial incentive out of it. But it shouldn’t … be the main reason you do the study.” A participant randomized to the $0 arm illustrated the concern that people motivated by money would be less committed to research:

I think if you [offer a] financial incentive at first upfront, anybody would take $150. Like okay, I’m going to just take it. When she [the research coordinator] walks away, I’ll put the watch on. When I get home, I’ll take it off and say I won’t do it [participate in the study]. … Well, if you say, hey, you’ll get $200 or $300 for doing something, pretty many people are going to say, ‘Oh shit, $200 just to walk around? Yeah, I’ll do that.’ It’s just too easy for people not to take.

In the prior quote, the participant refers to $150; payment for the ambulation trial was broken into two parts—an upfront payment of $150 and a $150 payment received upon trial completion. Participants understood that this payment structure was “[j]ust to make sure that I do stay in the program … an incentive to stay.”

Discussion

Here, we report the results of a qualitative study embedded in RETAIN, an RCT of incentives embedded in two real RCTs. This study builds on prior work on payment for research participation by analyzing both the recruitment discussion (in which participants first learned that they would be paid to participate in an actual study) and a subsequent semi-structured interview (in which participants were asked about the role of incentives in their decision making).

Results from RETAIN have previously been reported.¹⁰ Of particular relevance to this qualitative study were the primary RETAIN findings that, in the ambulation trial, financial incentives did not increase consent; there was no quantitative evidence of undue or unjust inducement; and there were no significant effects of incentive size on time spent reviewing the risks, perceived research risks, trial understanding, therapeutic misconceptions, or perceived coercion. The qualitative findings reported in this article add additional context to these findings.

Recruitment discussions were generally one-sided, and few participants reacted audibly when the research coordinator announced the financial incentive. Yet, nearly half of participants subsequently reported that they had been motivated to participate in the ambulation trial by the offer of money. Participants identified a number of other benefits associated with trial participation, including direct health benefits—many noted that ambulation was something they should be doing whether or not they were enrolled in research—and receipt of the wearable activity tracker. Altruistic motivation was also common. As noted previously, higher incentives were not effective at increasing enrollment in the ambulation trial. These qualitative findings lend support to the idea that “the benefits of the ambulation trial relative to the risks were perceived to be high, yielding higher baseline consent rates and fewer patients whose decisions could be altered by incentives.”¹¹

Consistent with the IRB’s determination, participants in our sample felt the ambulation trial was low risk and low burden. Approximately half asked the research coordinator clarifying questions about risks and burdens of participation during the recruitment discussion. In the semi-structured interviews, participants denied that the incentive had affected their judgment of research-related risks, a denial consistent with the RETAIN findings. Moreover, participants identified risks and burdens that would have led them not to participate in the ambulation trial, and some indicated that more money would not have sufficed to overcome those issues. Collectively, these findings are reassuring with respect to undue influence—that is, the common concern that an offer of payment to research participants will result in bad judgments. Results may be different in a study with a different risk profile or at higher levels of payment; however, a growing body of conceptual and empirical work suggests that undue influence need not dominate discussions of payment.¹²

An hypothesized ethical benefit of incentives is that they may reduce the likelihood that participants enroll due to therapeutic misconception—that is, a confusion of the goals of research (i.e., generalizable knowledge) with the goals of clinical care (i.e., individual benefit).¹³ Incentives have also been postulated to reduce tendencies for participants to be unaware that they are participating in research at all.¹⁴ Participants in this qualitative study recognized that they were enrolled in research, despite the fact that that the research coordinator did not consistently use the term “research” in the recruitment discussion. Overall, RETAIN found low rates of possible and likely therapeutic misconceptions, which did not differ by incentive groups.¹⁵

A commonly cited concern is that incentives for participation in research create unjust inducements—that is, they preferentially encourage enrollment among people of lower socioeconomic status, thereby resulting in an uneven distribution of research risks and burdens over the population.¹⁶ Several participants in this qualitative study volunteered information about their socioeconomic status, noting for example that they were “low income” or had “financial problems.” Yet they generally denied that money was their only—or even their primary—reason for enrolling in the ambulation trial. Past empirical work and now the RETAIN study supports the view that incentives do not result in unjust inducements.¹⁷ It is, therefore, important not to paternalistically limit incentive payments as a means of protecting worse-off participants.

One participant explicitly mentioned that she received SSI—monthly payments for individuals who have low income and are disabled—and implicitly expressed concern that receiving a financial incentive for participating in the ambulation trial could affect her SSI eligibility. Participant payments (excluding reimbursements) are taxable income. When payments exceed $600 annually, the payer must report them to the Internal Revenue Service.¹⁸ As income, payment may affect eligibility for income-based government benefits programs, including but not limited to SSI. It is important to address such considerations in recruitment discussions. Longer term, given the importance of promoting recruitment and retention for clinical trials and worries about fair access to clinical trials that offer a prospect of direct benefit, we recommend that at least some participant payments be excluded from taxation and income calculations.¹⁹ This would help address acknowledged financial barriers to research participation.²⁰ The Ensuring Access to Clinical Trials Act of 2015 excludes from certain benefits-eligibility determinations the first $2,000 per year received by individuals participating in clinical trials for rare diseases and could serve as a model for broader legislation.²¹

Consistent with prior work exploring participants’ motivations for enrolling in research, participants in this qualitative study reported experiencing multiple motivations, including but not limited to money.²² Yet, several participants expressed concerns that individuals who participated in research just for money were not participating for the “right reasons.” Many seemed to feel that it was better to participate for altruistic reasons or out of a desire for a direct medical benefit than for money, which is consistent with some work in the research ethics literature that accepts a role for payment but continues to emphasize the importance of preserving altruism.²³

Participants who had greater familiarity with research were less likely to describe the incentive as a deciding factor in their decision to enroll in the ambulation trial. While we do not think there is anything wrong with being motivated to participate in research by money, this finding does suggest patient education as a possible avenue for enhancing recruitment. Underpowered trials are a persistent ethical and scientific problem.²⁴ In addition to using incentives, acknowledging the essential contributions of participants to the success of the research enterprise may aid in recruitment.

Some participants expressed a belief that money could be a tool for retention as well as for initial recruitment. These individuals noted that payment for the ambulation trial was broken into two parts—an upfront payment and a payment at the end—and understood that this payment structure was meant to encourage them to remain in the trial for the duration. The practice of offering financial incentives to participants on the condition that they remain in a trial until they reach a prespecified study endpoint—that is, completion bonuses—is a recognized means of reducing attrition in clinical trials. Completion bonuses remain controversial due to concerns that they might coerce or unduly influence participants to not exercise their right to withdraw from research.²⁵ Yet, ethicists have argued that thoughtfully designed completion bonuses can be ethically acceptable.²⁶

Limitations

We had a relatively small sample for this qualitative study, though participants are reflective of participants in the ambulation trial overall.²⁷ Participants gave permission for audio recording of the recruitment discussion; knowledge of being observed may have affected their interaction with the research coordinator. Importantly, roughly half of individuals approached declined to participate in the ambulation trial, and we were unable to interview them to see what, if any, effect incentives had on this decision; their perceptions of about the ambulation study’s risks, burdens, and benefits may be different than the perceptions reported here. Finally, because the ambulation trial offered participants the prospect of direct medical benefit with low risks, these results may not generalize to participants’ views of incentives in trials with less favorable features.

Conclusion

The findings from this qualitative study add to a growing body of empirical and conceptual literature suggesting that payment is an ethically acceptable tool for promoting recruitment and retention in clinical trials. The problems with offering payment often loom too large in the imagination, but the problems of underpowered trials remain underappreciated. Therefore, we encourage IRBs to be guided by the evidence and relax restrictions on use of incentives in trials, like this one, that are low-risk and offer a prospect of direct benefit.