Choosing the Study Subjects: Recruiting

A good choice of study subjects serves the vital purpose, wanted by the sponsors, of ensuring that the findings in the study accurately represent what is going on in the population of interest. For this purpose, were created the inclusion and exclusion criteria for each study.

We know the inclusion criteria define the main characteristics of the target population that pertain to the research question. There are some crucial factors such as age, but the reason for this criteria may be just to achieve the optimal benefit-to-harm ratio of the drug. In the other hand, the exclusion criteria indicate those individuals who meet the inclusion criteria and would be suitable for the study were it not for characteristics that might interfere with the success of follow-up efforts, the quality of the data, or the acceptability of randomized treatment. Difficulty with language, psychological problems, alcoholism, and serious illness are common exclusion criteria that many subjects may not comply.

Falling short in the rate of recruitment is one of the commonest problems in clinical research. While recruitment is ongoing, it is important to closely monitor progress in meeting the recruitment goals and tabulate reasons for falling short of the goals. Understanding why potential subjects are lost to the study at various stages can lead to strategies for reducing these losses.

Sometimes recruitment involves selecting subjects who are already known to the members of the research team, for example some patients attending the principal investigator’s clinic. Here the big concern is to present the opportunity for participation in the study fairly, making clear the advantages and disadvantages. In discussing participation, the investigator must recognize the ethical dilemmas that arise when his or her advice as the patient’s physician might conflict with his or her interests as an investigator.

Often, recruitment involves contacting populations that are not known to the members of the research team has previous experience with the approaches for contacting the prospective subjects. These include screening in work settings or public places such as shopping malls; sending out large numbers of mailings to listings; advertising on the Internet; inviting referrals from clinicians; carrying out retrospective record reviews; and examining lists of patients seen in clinic and hospital settings. Some of these approaches, particularly the last two, involve concerns with privacy invasion that must be considered by the institutional review board.

At Althian, we are always striving to achieve our recruitment goals and with the right knowledge and experience earned by the years, the recruitment staff along with the investigator designs and implement strategies for recruiting as much subjects as we can, always taking care of the fulfilling of the inclusion and exclusion criteria. Please do not hesitate to contact us for more information about recruitment.



Stephen B. Hulley et. al. Designing Clinical Research. 4th edition. 2013.