Recruitment strategies and patient selection in clinical trials for Parkinson's disease: Going viral and keeping science and ethics at the highest standards

Introduction: Enrollment of an adequate number of suitable candidates is a critical component of good quality randomized controlled trials (RCTs). Parkinson's disease (PD) is a highly heterogeneous disease and recruiting a large and homogeneous sample of patients is often challenging. Further, PD patients are often elderly, cognitively impaired and disabled, thus requiring the assistance from their caregivers for participation in RCTs. Only a limited number of studies have explored the effectiveness of recruitment strategies and PD patient selection in clinical trials. We aim to review the four crucial recruitment components of RCTs (i.e. infrastructure, nature of the research, recruiter characteristics and participant characteristics) with particular implications in PD, and to explore strategies to improve recruitment and patient selection in RCTs in PD. Conclusion: Movement disorders centers have a key role in managing recruitment and patient selection in RCTs in PD. Key recommendations within the infrastructure component are to improve trust and communication between patient and participant, and to consider the diversity, perceived disadvantages, and health care accessibility of the participants. Further, study designs that involve participant's opinions and considers placebo and lessebo effects are highly recommended for the nature of the research component of RCTs. Finally, a team-based approach with recruiters and participants that establishes relationships between researchers and the community and addresses ethical considerations are encouraged as part of the recruiters and participants components. Finally, we envisage a greater usage of internet-based strategies for clinical trials recruitment in PD with the goal of 'going viral' with the recruitment.