Reporting the Recruitment Process in Clinical Trials: Who Are These Patients and How Did They Get There?

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The summary below is from the full report titled "Reporting the Recruitment Process in Clinical Trials: Who Are These Patients and How Did They Get There?" It is in the 2 July 2002 issue of Annals of Internal Medicine (volume 137, pages 10-16). The authors are C Gross, R Mallory, A Heiat, and HM Krumholz.

What is the problem and what is known about it so far?

When researchers perform clinical studies comparing one treatment with another, they often use an experimental design known as a randomized, controlled trial (RCT). This design ensures that patients are randomly assigned to treatment groups in a way that will not bias the results by putting many people who are likely to respond favorably into one group and many who are not likely to respond into another. Although RCTs are generally accepted as the strongest way to design a clinical study, the usefulness of the findings depends not only on the strength of random assignment but also on how well the experimental patients represent all patients with the particular disease being studied.

Why did the researchers do this particular study?

The researchers wanted to find out whether RCTs published in good medical journals provided enough information about the selection of study participants to allow readers to judge whether most people with a particular disease could be expected to have the same results as the participants in the experiment.

What was studied?

172 RCTs involving humans that were published in four widely respected medical journals over a 1-year period beginning April 1, 1999.

How was the study done?

All RCTs published during that year were identified, and articles appropriate for evaluation were selected for review. The researchers then recorded how many articles provided information about the number of people screened for eligibility to participate in the study, how many described the number of people who were found to be eligible for participation, and how many people were actually enrolled. In addition, the researchers recorded the type of study being performed, where the money came from to perform the study, and the severity of the disease being studied.

What did the researchers find?

Only about half of the published RCTs reported the number of potential participants who were screened for eligibility. Forty-three percent reported how many people were eligible for participation, and 28% reported enough information to calculate what proportion of the screened population was found to be eligible for participation. The researchers also found that in order to recruit each participant for the study, more people needed to be screened if the disease being studied was more severe. Funding source did not appear to affect recruitment.

What were the limitations of the study?

Only four medical journals were included in the study, and RCTs they published may not be representative of all published RCTs.

What are the implications of the study?

More information needs to be provided about the people who take part in RCTs in order for clinicians to be able to judge whether the findings are applicable to all patients with a particular disease.