RECRUITMENT AND RETENTION: TWO OF THE MOST IMPORTANT, YET CHALLENGING, TASKS IN BEHAVIORAL INTERVENTION RESEARCH
DANIEL E. JIMENEZ AND SARA J. CZAJA
The research participants who volunteer or give permission for themselves, their clinical and health data, and their tissues to be used in clinical research are the heart of the clinical research enterprise.
—Sung et al. (2003, p. 1279).
Over the past 50 years, as a result of breakthroughs in basic biomedical and behavioral intervention research, many strategies for improving health and quality of life have been discovered, and there has been an unprecedented supply of information related to them. Development of these discoveries and translation to individuals, communities, and clinical settings are predicated upon the participation of diverse study participants in intervention trials (George, Duran, & Norris, 2014; Sung et al., 2003). A carefully developed, implemented, and evaluated recruitment and retention plan ensures adequate representation in intervention studies from diverse groups of individuals (e.g., age, gender, ethnicity), which in turn is essential to support the generalizability of interventions that will ultimately positively impact the health and well-being of populations (Hendricks-Ferguson et al., 2012; Sung et al., 2003). Given the pace of discovery in biomedical science and the increased complexity of health and social issues, there will be an increased need for behavioral intervention research. Accordingly, the number of behavioral intervention research studies will continue to increase (Sung et al., 2003) and in turn, there will be an increased demand for research participants from diverse populations.
It is well established that the effective recruitment and retention of individuals in behavioral intervention research trials are critical to the development of a successful intervention at all stages of the pipeline. Yet, despite the long history of intervention research, recruitment and retention of study participants remain a central challenge to most investigators (Sung et al., 2003). There are two main goals of recruitment: to enroll participants into a study who are representative of the target population and to enroll sufficient numbers of participants to meet the sample size and power requirements for the study. Many studies fall short on recruitment and fail to achieve these goals or to do so within a reasonable time frame. Practical considerations include one’s budget and access to resources such as staff to help with recruitment and retention. Allocation of funds to this effort is critical as it takes resources to assure adequacy in recruitment methodology and also to employ effective retention strategies. Time taken to recruit research participants is important for both logistical and scientific reasons. From a logistics standpoint, lagging recruitment results in higher costs, frustration, and issues related to treatment fidelity and staff effort. From a scientific standpoint, lagging recruitment may make the trial outdated (e.g., a new intervention may be introduced), or supplanted by other researchers who address the research questions sooner. This could delay the time that an effective intervention could be actually implemented in community settings. Recruitment lags can also adversely impact those already enrolled in a trial (Friedman, Furberg, & DeMets, 2010). For example, participants enrolled in a group therapy study would have to wait an indefinite amount of time to receive a much needed treatment owing to a delay in recruiting the required number of participants for the group. Moreover, recruitment lags generate concern from the funding agency about the ability of the research team to successfully conduct the trial.
Retention, the process of keeping participants in a study, also poses many challenges, especially in longitudinal studies or studies that involve vulnerable populations such as those who are ill or older (e.g., the “older old”). High rates of participant dropout are costly and have a significant impact on the external validity of the research findings. For example, high rates of attrition can lead to sampling biases if participants with certain characteristics (e.g., educational level or age) are more likely to drop out of a study and can also cause unevenness among study groups (e.g., those in the control group have higher rates of attrition than those in the intervention group or vice versa). Obviously, attrition has important implications for sample size and the statistical power of a study
Overall, problems with recruitment and retention: disrupt study timelines; create additional workload for study staff and problems with frustration, low morale, and additional costs; pose threats to the internal and external validity of a study; and can ultimately lead to the abandonment of a trial. A common reason for problems with recruitment and retention is a lack of knowledge of recruitment issues and planning on the part of the investigator or study team. Often, investigators have an unrealistic view of the availability of participants and the effort required to enroll and maintain participants in a study. As noted by Friedman and colleagues (2010), “successful recruitment depends on developing a careful plan with multiple strategies, maintaining flexibility, establishing interim goals, preparing to devote the necessary effort and obtaining the sample size in a timely fashion” (p. 103).
Unfortunately, in the intervention literature, reports of the baseline characteristics or the results of an intervention trial typically provide limited detail describing recruitment procedures or the “success rates” of the various methods used to enroll participants. In fact, a review of 172 randomized controlled trials (RCTs) published in high-impact medical journals over a year’s period (April 1, 1999 to April 1, 2000) (Gross, Mallory, Heiat, & Krumholz, 2002) indicated that only a small percentage provide detailed information about patient recruitment processes. Thus, researchers generally have little guidance when developing recruitment plans.
The goals of this chapter are twofold: (a) to describe the most common barriers to successful recruitment and retention and (b) to provide strategies that can be used to enhance the enrollment and retention of participants in behavioral intervention research. Our emphasis is on ways to enhance recruitment and retention efforts and avoid common pitfalls and problems. Recruitment and retention will always be a challenge, and there is no magic formula to ensure complete success. However, having an awareness of the challenges and strategies to meet them can help to improve the efficiency and effectiveness of the recruitment process. We begin with a discussion of common challenges concerning recruitment and retention that confront investigators in behavioral intervention trials. We then describe general strategies to enhance recruitment and retention followed by specific recommendations for recruiting and retaining the desired, representative sample.