MEASURING SITE ENROLLMENT PERFORMANCE
Table 3: Measures of Site Enrollment Performance
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Even with improved site activation, Clinical Trial B uses many more sites (167 vs. 44), and significantly longer enrollment
duration (13 months vs. 9 months) than Clinical Trial A. If we look at the above study and this time consider a hypothetically
modified Clinical Trial B—call it Clinical Trial BM—reaching a maximum number of sites activated in 7.5 months instead of
the original 10 months. That brings the SEI up from 0.45 (Clinical Trial B) to 0.55 (Clinical Trial BM), the same as in Clinical
Trial A. As shown in the figure below, the total chart area beneath the straight lines then becomes the same. (See Table 3.)
As noted above, improvement in site activation can reduce the total number of sites needed from 204 in Clinical Trial B to
167 in Clinical Trial B[M]. But 167 sites, 13 months, and 565 patients is still quite different from the 44 sites, 9 months,
and 700 patients in Clinical Trial A. The 44 sites in Clinical Trial A, on average, performed much better in enrollment than
those in Clinical Trial B[M.] When we calibrate the TRUE sites by the SEI of 0.55 for both Clinical Trial A and Clinical Trial
B[M], it gives 92 sites (167 sites x 0.55) for Clinical Trial B[M] and 24 sites (44 sites x 0.55) for Clinical Trial A. Therefore,
the Average Site Enrollment Rate (ASER) is 3 patients per site per month (700 patients/24 sites/9 months) for Clinical Trial
A, whereas ASER is 0.5 patients per site per month (565 patients/92 sites/13 months) for Clinical Trial B.
In other words, Average Sites Enrollment Rate (ASER) is independent of clinical trial enrollment duration. For example, if
you have four sites opened for enrollment for one, three, five, and seven months, respectively, and enrolled 160 patients
in total, the ASER for the four sites is 2.5 patients/site/month (160 patients/4 sites/(1+3+5+7) months). The enrollment cycle
time for this clinical trial could be 7 months or 10 months, or even longer—the ASER for the four sites remains 2.5 patients/site/month.
(Generally speaking, it is safe to assume that the site opened for enrollment for seven months is likely the best performer
among all the four sites.)
Now we can see the picture more clearly: If we were able to select the same number of high enrolling sites in Clinical Trial
B as we did in Clinical Trial A, we would only need 34 sites to enroll 565 patients (34 sites = 204 sites x 0.5 patients per
site per month/3 patients per site per month) in 13 months. In other words, the enrollment performance (ASER) of the sites
in Clinical Trial B and divide that by the enrollment performance (ASER) of the sites selected in Clinical Trial A, that is
the portion of the 204 sites needed, which equals to 34 sites
By now, we can see the financial consequences caused by the differences in site activation effectiveness and site enrollment
performance. Assuming the cost to activate a site is $20,000 (a representative yet conservative industry estimate), needing
160 more sites in Clinical Trial B compared to Clinical Trial A means $3.2 million more in site activation costs. Assuming
a site management fee is $1,500 per site per month, and the study duration is 8 months, there would be $1.9 million more in
site management spending for Clinical Trial B.
By adding the extra site activation fees and extra site management fees together, the cost comes to a hefty sum of $5.1 million:
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