Review
More than the money: A review of the literature examining healthy volunteer motivations

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Abstract

Background and objective

Few existing data report the motivations of healthy volunteers in clinical research trials. Some worry that volunteers consider only financial motivations. This study summarized and analyzed existing empirical research on self-reported motivations of healthy volunteers participating in studies not intended to offer benefit from participation.

Study selection

A systematic PubMed search was conducted. Inclusion criteria captured English-language empirical studies on the self-reported motivations, reasons, or factors influencing the decision of healthy volunteers to enroll in clinical research. Thirteen studies involving more than 2000 healthy volunteers met the criteria and were included in this review.

Data extraction

Independent review by the authors and extraction of information about the sample, methodology and objectives of the motivations study, description of the clinical trial and whether participation was actual or hypothetical, reported primary and secondary motivations of the healthy volunteers, risk evaluation, and reported differences in motivations related to sociodemographic variables.

Results

This review showed that although financial reward is the primary motivation for healthy volunteers to participate in clinical trials, financial motivations are one among many other reported motivations, including contributing to science or the health of others, accessing ancillary healthcare benefits, scientific interest or interest in the goals of the study, as well as meeting people and curiosity. Volunteers consider risk when making a decision about participation.

Conclusions

Although financial incentives are important in recruiting healthy volunteers, their motivations are not limited to financial motivations. Further research is needed to examine motivations in different contexts and countries, the decision making of healthy volunteers, and the dynamics of repeat participation.

Introduction

Healthy volunteers for drug development trials and other research are exposed to risk and discomfort without any expectation of health benefits. These volunteers are essential to the development of new drugs and biologics and for testing new formulations, and invaluable for investigating drug safety, dosing, and pharmacokinetics. However, few have examined why healthy individuals volunteer to participate in research. While clinical research participants who suffer from disease are often motivated to participate in research in order to gain possible therapeutic benefits and free medical treatment, or to help fight or better understand the disease that afflicts them [1], [2], [3], [4], the motivations of healthy research participants are likely to be quite different. The widespread perception is that healthy volunteers who enroll in clinical research are motivated strictly by financial reward [5], [6]. For instance, Carl Elliot asserts: “the relationship between testers and test subjects has become, more nakedly than ever, a business transaction.” [7] To the extent that this is true, several ethical issues arise. Some commentators have suggested that volunteers who are only motivated by payment disregard risks or may not be able to properly assess the risk of a particular study [8]. Others worry that payment for research participation disproportionally attracts low income volunteers, and thus result in research that disproportionately burdens the poor [8], [9], [10], [11], [12] enrolls an unrepresentative cohort [13] or creates incentives to lie about health history [10], [14]. Empirical evidence that supports these concerns is limited. Further, financial motivations do not necessarily preclude other motivations or considerations. Our goal with this review is to critically examine existing data to evaluate whether it supports the implication that the “business transaction” aspect of research with healthy volunteers is necessarily negative.

Currently, no systematic review of the literature examines research on healthy volunteer motivations. In this paper, we examine, classify and compare empirical studies which measure self-reported motivations, reasons for participation, and/or decision making processes for healthy volunteers participating in drug studies and other clinical research not intended to offer direct health benefits.

Section snippets

Systematic review

A comprehensive PubMed search limited to the English language only used a combination of Medical Subject Heading (MeSH) terms and keywords reflecting three search criteria (Fig. 1): human subjects research, motivations or reasons for participation in research, and decision making by healthy volunteers (rather than patient volunteers or physicians). The MeSH term “Empirical Research” or “Biomedical Research” fulfilled the first criterion, human subjects research. MeSH terms “Motivations” or

Results

Of the thirteen [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27] studies identified, six were conducted in the United States [17], [18], [19], [21], [24], [26], six in Europe [15], [16], [22], [23], [25], [27], and one in Malawi [20]. The Mtunthama study, which took place in Malawi, was the only published research on this topic from a developing country identified by our review. Each of the thirteen studies used quantitative methods to describe and compare different

Complex motivations

Although not the sole motivation for all participants in any of the studies, financial reward, as noted above, was one of the main motivations for participation in twelve of thirteen studies [14], [15], [16], [17], [18], [19], [21], [22], [23], [24], [25], [26], [27], and the principal motivation in eight of the thirteen studies [15], [16], [17], [18], [23], [24], [25], [26]. In fact, one of the volunteers interviewed by Kass et al. made it clear that money is necessary to incentivize research

Further discussion

Although commentators speculate about how financial motivations affect healthy research volunteers, there are few empirical studies on healthy volunteer motivations. Commentators denounce payment as leading to risk distortion, a disproportionate research burden for the poor, and destruction of altruistic motivations for research participation, because payment is assumed to be an all consuming motivator. The thirteen identified studies reviewed here which focused on the positive motivations of

Conflicts of interest

There are no conflicts of interest to report.

Acknowledgments

Funding support: this review was funded by the National Institutes of Health Clinical Center Department of Bioethics. The authors had complete control over the design and conduct of the review; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.

Access to data: this review was supported by the National Institutes of Health Clinical Center Department of Bioethics. The authors had full access to all of the data in the study and

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