GlobalData has found that in both multinational and single-country trials run in Brazil between January 2001 and July 2018, the higher the number of sites there were in a trial, the lower the enrollment rate.

The highest count of clinical trials (shown by the size of the bubble), with 65% of the total, was trials with a site count of above 50.

The second highest count of clinical trials, with 18% of the total, was clinical trials with a site count of 21–50. The enrollment rate is 26.5 subjects/site/month for the single-site trials, compared to only 0.7 subjects/site/month in trials with a site count over 50.