A scoping review to investigate recruitment and retention of people with dementia in clinical trials
Authors: Shawaqfeh B , Hughes C M , McGuinness B , Barry H E 
Published: April 2024

Abstract

Introduction
The literature acknowledges difficulties in recruiting people with dementia (PwD) to research studies. Despite efforts of researchers and policymakers to improve participant recruitment and retention in clinical studies,[1] challenges remain.[2] Further work is needed to describe recruitment and retention of PwD in clinical studies and strategies used to promote these activities.

Aim
This scoping review aimed to investigate recruitment and retention of PwD in clinical trials focused on evaluating the pharmacological management of cognitive symptoms of dementia.

Methods
Five electronic databases (Medline, Embase, PsychINFO, Scopus, Web of Science) and the International Clinical Trials Registry Platform were searched using a variety of search terms to identify articles published in English from date of inception until July 2023. All registered, unregistered, published, and unpublished randomised controlled trials that evaluated pharmacological treatments for cognitive symptom management among PwD, with a mean age ≥65 years and dementia of any sub-type or stage were included; studies were not excluded based on setting. Two reviewers independently reviewed full texts of potentially eligible records. Data were extracted by one reviewer using a table constructed in Microsoft Excel; a 10% subset was checked by a second reviewer. Findings were summarised using frequencies and percentages and/or narratively presented in tables.

Results
In total, 3,253 records were found, with 2,953 records remaining after removal of duplicates. Following title/abstract screening, 229 full-text articles were assessed for eligibility. A total of 129 records met the inclusion criteria for this review. Fifty-eight studies (45.0%) recruited community dwelling PwD. Common reasons for participants to be excluded from trials were having no carer present (n=128 studies, 99.2%), using specific medications such as anticholinergic medications (n=28 studies, 21.7%), and being unable to swallow tablets without crushing (n=10 studies, 7.7%). A limited number of studies (n=45, 34.9%) provided details about how they recruited participants. A variety of different recruitment sites were used including clinical research facilities (n=16, 12.4%), memory clinics (n=17, 13.2%), general practices (n=2, 1.6%), nursing homes (n=2, 1.6%), hospitals (n=2, 1.6%). Few studies recruited through advertisements in local newspapers/radio stations (n=2, 1.6%). Only one study reported that PwD and their carers were supported by research/clinical staff throughout the trial to improve participant retention. The mean sample size was 439 participants, and the mean retention rate was 73.5%. On average, 99 participants per study withdrew from the clinical trials, with common reasons for withdrawal being adverse events (n=45 participants per study), carer no longer available (n=37 participants per study), and death (n=12 participants per study).

Conclusion
This study has provided important evidence on recruitment and retention of PwD in clinical studies. The findings highlight how poorly recruitment is described in the literature and it is unclear what strategies were used to promote recruitment and retention. Researchers working in this field should consider this when disseminating their work. Whilst a quality assessment of included studies was not undertaken, this is acceptable in scoping reviews. Future research should focus on enhancing transparency of reporting recruitment and retention of PwD in clinical research.

References
1. Fargo KN, Carrillo MC, Weiner MW et al. The crisis in recruitment for clinical trials in Alzheimer’s and dementia: An action plan for solutions. Alzheimers Dement. 2016;12(11):1113-1115.
2. Shawaqfeh B, Hughes CM, McGuinness B et al. A systematic review of interventions to reduce anticholinergic burden in older people with dementia in primary care. Int J Geriatr Psychiatry. 2022;37(6):10.1002/gps.5722.