FIGURE 7-2 Patient recruitment rates for four type 1 diabetes trials.

FIGURE 7-2 Patient recruitment rates for four type 1 diabetes trials.

SOURCE: Greenbaum, 2009. Reprinted with permission from Carla Greenbaum 2009.

discussed some of the factors associated with each study that she believes affected their ability to attract patients in an efficient manner.

For each trial depicted in Figure 7-2, the sites were large diabetes centers that are highly committed to recruiting patients. Thus, differences in recruitment rates should not be attributable to variation in the commitment level of trial sites. The trial that recruited 4.1 subjects per month required daily, chronic medication therapy. In the trial that recruited 5.4 patients per month, the drug treatment was two doses (not a chronic therapy), and some follow-up visits were required. The study with the most successful patient recruitment rate is surprising because it involved younger subjects, who, as noted, are typically difficult to recruit, for an intravenous (IV) infusion over 24 visits, one visit per month. In contrast, the study with the lowest recruitment rate has yet to recruit the 10 subjects it requires. Greenbaum explained that this is a phase I study, started at only one site and including only individuals aged 18 and older. In addition, subjects have to have been diagnosed with type 1 diabetes at least 4 years previously, but still have significant insulin secretion to qualify for enrollment in the study.

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