Recruitment of pre-dementia participants: main enrollment barriers in a longitudinal amyloid-PET study

BACKGROUND

The mismatch between the limited availability versus the high demand of participants who are in the pre-dementia phase of Alzheimer's disease (AD) is a bottleneck for clinical studies in AD. Nevertheless, potential enrollment barriers in the pre-dementia population are relatively under-reported. In a large European longitudinal biomarker study (the AMYPAD-PNHS), we investigated main enrollment barriers in individuals with no or mild symptoms recruited from research and clinical parent cohorts (PCs) of ongoing observational studies.

METHODS

Logistic regression was used to predict study refusal based on sex, age, education, global cognition (MMSE), family history of dementia, and number of prior study visits. Study refusal rates and categorized enrollment barriers were compared between PCs using chi-squared tests.

RESULTS

535/1856 (28.8%) of the participants recruited from ongoing studies declined participation in the AMYPAD-PNHS. Only for participants recruited from clinical PCs (n = 243), a higher MMSE-score (β =  - 0.22, OR = 0.80, p < .05), more prior study visits (β =  - 0.93, OR = 0.40, p < .001), and positive family history of dementia (β = 2.08, OR = 8.02, p < .01) resulted in lower odds on study refusal. General study burden was the main enrollment barrier (36.1%), followed by amyloid-PET related burden (PCresearch = 27.4%, PCclinical = 9.0%, X2 = 10.56, p = .001), and loss of research interest (PCclinical = 46.3%, PCresearch = 16.5%, X2 = 32.34, p < .001).

CONCLUSIONS

The enrollment rate for the AMYPAD-PNHS was relatively high, suggesting an advantage of recruitment via ongoing studies. In this observational cohort, study burden reduction and tailored strategies may potentially improve participant enrollment into trial readiness cohorts such as for phase-3 early anti-amyloid intervention trials. The AMYPAD-PNHS (EudraCT: 2018-002277-22) was approved by the ethical review board of the VU Medical Center (VUmc) as the Sponsor site and in every affiliated site.

Older adults in hematologic malignancy trials: Representation, barriers to participation and strategies for addressing underrepresentation

Despite a high incidence of hematologic malignancies in older adults, available data indicate that there is disproportionately low representation of adults ≥65 years with hematologic malignancies (greater in patients ≥75 years) in clinical trials. Biological and clinical differences between older and younger adults and diversity within older patients necessitate adequate representation of the older subpopulation in hematologic malignancy trials. This would allow trial results to be generalizable and inform treatment decisions in the older patient population. Restrictive eligibility criteria may be barriers to adequate representation, as older adults do not typically meet these criteria. Efforts to broaden eligibility criteria in clinical trials have been proposed and may promote enrollment of a representative older population with hematologic malignancies. Collaboration among a diverse group of stakeholders will be needed to implement current proposals and evaluate their impact on increasing representation of older adults in trials evaluating therapies for hematologic malignancies.