Enrollment-Cost and Recruitment Effectiveness in a dTMS Clinical Trial for Older Adults with Depression: A Mixed-Methods Analysis of Recruitment Strategies, Facilitators, and Barriers.

OBJECTIVE: Recruitment challenges are inherent in clinical research, and are particularly pronounced in older adults with depression, who often face unique barriers such as medical comorbidities and infrequent help-seeking behaviour. Neurostimulation techniques, like deep transcranial magnetic stimulation (dTMS), are often unfamiliar to patients within the healthcare system. Existing literature offers limited insight into the costs and practical guidance associated with recruitment strategies in dTMS trials. This study aimed to address these gaps by investigating the cost-effectiveness of various recruitment strategies for dTMS trials among older adults. Furthermore, we examined potential facilitators and barriers to recruitment. METHODS: This mixed-methods retrospective analysis examined recruitment data from our pilot study investigating the effects of dTMS in older adults with depression. We assessed diverse recruitment methods by analyzing enrollment rates and conducting an enrollment-cost analysis. Recruitment-related barriers and facilitators were identified using a theoretical thematic analysis. RESULTS: Over a 14-month period, we received 185 referrals, yielding 22 enrollments. Healthcare provider outreach to affiliated mental health clinics was the most effective recruitment method, with an enrollment-cost rate (ECR) of 0.00189 ($537.63 CAD/person enrolled). The second most effective recruitment method was Facebook, producing an ECR of 0.00099 ($925.93 CAD/person enrolled). Social support from research personnel was a potential facilitator of recruitment, while time-intensiveness and accessibility challenges were noted as potential barriers. CONCLUSION: Our findings highlight both healthcare provider outreach within mental health clinics and Facebook advertising as effective recruitment strategies. Future research is warranted to evaluate recruitment-related facilitators and barriers to dTMS interventions for older adults with depression.