Nine out of 10 clinical trials worldwide meet their patient enrolment goals, but meeting those targets typically means that drug developers need to nearly double their original timelines, according to new research.

Most drug sponsors and contract research organisations (CROs) rely on a limited number of traditional recruitment and retention tactics, says the study, which is published by the Tufts Center for the Study of Drug Development (CSDD). These include physician referrals and ads in newspapers and on television and radio, but sponsors and CROS have yet to embrace non-traditional approaches such as social media, according to the analysis, which is based on more than 150 clinical studies involving nearly 16,000 clinical sites.

"Patient recruitment and retention are among the greatest challenges that the clinical research enterprise faces today, and they are a major cause of drug development delays," says Ken Getz, director of sponsored research at Tufts CSDD, which publishes the study findings in the January/February issue of the Center's Impact Report.

The analysis also finds that 89% of all clinical trials meet enrolment goals, with site activation rates reflecting success with study start-up and speed to recruit the first patients. The highest site activating rates are in Western Europe (93%), Eastern Europe (92%) and Asia/Pacific (91%).

Enrolment rates vary by region and range from 75% to 98% of targeted levels, with Asia/Pacific and Latin America achieving the highest rates. However, 11% of sites in a given trial typically fail to enrol a single patient, while 37% under-enrol, 39% meet their enrolment targets and 13% exceed their targets, the study finds.