Note that although there are about 50 patients attending the clinic, the investigator estimates that only about 5 per month will be willing to participate, eligible, and complete the study. This reflects the reality that only a small proportion of potentially eligible individuals may be interested in your study.
13.2 Recruitment and Retention Is Part of Planning
In addition to determining if the study is feasible, there are many other reasons that methods of recruiting and retaining participants must be part of your planning. If you are writing a proposal, then you must convince the potential sponsor that you can find and retain the number of participants you specified and budgeted for this activity. If the study has any longitudinal component, you must have a realistic estimate of the proportion that can be expected to complete the study to determine the number of participants that must be enrolled to achieve the specified number of participants completing the study. This may also impact the feasibility of the design.
You have designed a crossover study with 3 treatment periods of 8 weeks each and a 2-week washout period between each treatment period. This is a very demanding study for the participants, who would need to participate for a total of 28 weeks. Is it likely that you can find enough participants in the population at your center that will agree to this, and will stay in the study? If the study only requires a small number of participants to complete the 3 treatment periods, or if the participants are people with whom you interact on a regular basis, such as patients in a diabetes clinic, then this study may be feasible. Recruiting your own patients, however, raises the potential for coercion, discussed in Section 3.3. Otherwise, since it is likely that there will be a lot of dropouts, it may be better to do this study using a parallel group design with each participant receiving one treatment.
Recruitment and retention are costly, time-consuming tasks, and you must allow for adequate personnel time and financial support. The personnel who interact with the participants are the key to successful recruitment and retention. They must be readily accessible to answer questions, be nonjudgmental, and show respect for the participant at all times. Most importantly, the staff members must be problem solvers. If study staff are evaluating participants, filling out forms for the study, entering data, and performing all the other duties necessary to keep a study running, will they have the time needed to communicate with participants and to address their concerns? Your staffing plan must allow sufficient time for nonspecific interaction with participants.
13.3 Locating and Recruiting Participants
Locating and recruiting participants can be done in many ways, listed in Table 13.1. The approaches range from a targeted appeal to a limited group (e.g., clinic patients, referrals from specialists in the disease), to broad, “shotgun” approaches (e.g., Internet and media advertising). In between these extremes are more general but still targeted approaches (presentations to support groups and posting to Internet groups focusing on the groups of interest, etc.).
You intend to recruit participants with a specific condition from clinics in your institution. You must review the clinic reports to ensure that there are enough participants available who will meet your inclusion and exclusion criteria, assuming that most will refuse to participate. If there are not enough patients in your clinic, you may need to expand the eligible population by making arrangements with other institutions. This may be an informal agreement with a neighboring institution or with specialists in the community to refer patients, or formal arrangements with institutions in other locations.
Recruiting from a clinic might require placing posters or pamphlets written in layman’s language, often in multiple languages, in the clinic’s waiting area with information on the study, or arranging for clinic personnel to describe the study briefly and ask prospective participants if they would be willing to be contacted about participating. Sometimes a recruiter for the study, with the approval of the Institutional Review Board (IRB), will attend the clinic to ask patients if they would be willing to talk about the study while waiting, and to answer questions about it.
If participants are to be recruited from the general population, methods to advertise the study include word of mouth (usually not sufficient), advertising on local bulletin boards, newspaper and radio advertising, the Internet, presentations at community groups, and the like. Occasionally mass mailings are used to locate study participants, but this is not very efficient and is only done for very large studies. Mailing lists based on basic characteristics such as age and sex can be purchased from marketing firms, but this is expensive. Frequently, a brochure and a website describing the study will be prepared. Some studies use professional recruiters, although this is also expensive. Many institutions have staff members who aid investigators in developing and implementing plans for recruiting and who can be reached in the evenings or weekends.
