Objective: To understand successful recruitment and retention strategies for clinical research studies in Parkinson’s disease (PD)

Background: Half of all clinical trials do not reach their recruitment target and a quarter experience attrition of more than 10%. This risks a loss of statistical power as well as selection bias that could lead to a mismatch between study participants and the target population. Retention is particularly important in trials that require long-term follow up such as those testing disease modifying therapies.

Method: We conducted a scoping review using the Population (1), Intervention (2), Comparator (3), Outcome (4) and Study Design (5) (PICOS) framework to search and screen literature within five databases. Papers were included if they: (1) investigated PD patients; (2) had a recruitment or retention strategy in an interventional or observational PD study; (3) had a comparator present such as standard practice or a different strategy; (4) evaluated a change in recruitment or retention rate; and (5) used a quantitative or mixed methods design to evaluate effects. Papers had to be in English and published between 2008 and 2023. Qualitative studies, review papers, cell and gene therapy and surgical trials were excluded. To gain further insights into the effectiveness of the PICOS at identifying articles aligned with the outlined objectives, reasons for failing the article screening stage were recorded.

Results: Searches identified 4,608 records of which six described and evaluated recruitment strategies. No articles were found that evaluated retention strategies. Papers discussing retention that were excluded explored barriers and motivators to research compliance using surveys (n=5), qualitative interviews (n=8) and narrative discussion (n=2). Of these, nine focused on observational studies, two on interventional studies of disease modifying therapies and four on general research.

Conclusion: There are no research studies that evaluate the effectiveness of retention strategies in clinical research studies of PD, leading to a lack of evidence on what works best. Future work should use existing qualitative and survey studies to design appropriate interventions that can be formally tested as a study within a trial (SWAT), particularly within studies with longer-term follow up.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/retention-strategies-in-parkinsons-disease-clinical-studies-findings-from-a-scoping-review-of-recruitment-and-retention-strategies/