Strategies to improve recruitment in mental health clinical trials: a scoping review (RE-MIND study).

Background: Lower-than-expected recruitment continues to be one of the major causes of trial delays, and trials to improve mental health are no exception. Indeed, recruitment challenges in trials of vulnerable populations, such as those living with mental health illness, can even be exacerbated. To address this, researchers are turning to digital and online recruitment strategies, e.g. web-based approaches and multi-media in order to (1) increase recruitment efficiency (recruit to target and on time) and (2) improve diversity in mental health clinical trials to be more inclusive and reduce health inequity. There is, however, inconclusive evidence on the success of digital and online recruitment strategies in mental health clinical trials. The RE-MIND study comprised a scoping review to assess the impact of using such recruitment strategies in mental health clinical trials to inform a more systematic scoping review.

Methods: A cohort of 191 recently published RCTs and randomised feasibility studies were identified from the NIHR Journals Library and top two mental health journals (based on citation metrics), Lancet Psychiatry and JAMA Psychiatry. Population characteristics including gender, ethnicity and age were summarised for inclusivity using descriptive statistics, and recruitment strategies were compared to examine differences in their success in recruiting to target.

Results: After screening, 97 articles were included for review. The review findings showed no evidence that offline or mixed strategies were superior for achieving recruitment targets in mental health trials. However, there was a suggestion that trials using a mixed recruitment strategy improved inclusivity and tended to recruit closer to the target.

Conclusions: The key finding was that consideration should be given to a mixed methods approach to recruitment not only to enable wider and more diverse participation in mental health trials but also to realize greater efficiency.