Changes in key recruitment performance metrics from 2008-2019 in industry-sponsored phase III clinical trials registered at ClinicalTrials.gov.

Recruitment duration for industry-sponsored phase III clinical trials have increased significantly during the last 12 years from an average recruitment period of 13 months (IQR 7-23) in 2008-2011 to 18 months (IQR 11-28) in 2016-2019 (p = 0.0068). Further, phase III clinical trials have increased the number of registered sites per clinical trial by more than 30% during the last 12 years from a median number 43 sites (IQR 17-84) in 2012-2015 to 64 sites (IQR 30-118) in 2016-2019 (p = 0.025), and concurrently, the number of participants enrolled in clinical research has decreased significantly from 2012-2015 and 2016-2019 (p = 0.046). We believe that these findings indicate that recruitment for phase III clinical trials is less effective today compared to 12 years ago.