# Feasibility and acceptability of remote APOE-genotyping among research volunteers of an online recruitment registry (The Dutch Brain Research Registry)

## TL;DR

This study shows that at-home APOE-genotyping is feasible and well accepted by volunteers in an online registry for Alzheimer's prevention research.

## Contribution

The study demonstrates the practicality of remote APOE-genotyping and introduces a prescreening strategy to improve recruitment efficiency.

## Key findings

- High feasibility with 89% participation, 90% swab return, and 99% genotyping success rates.
- 27% of participants were APOE-ε4 heterozygotes and 2% homozygotes.
- Prescreening with family history reduced the number of invitations needed to identify APOE-ε4 carriers by a third.

## Abstract

Participant recruitment for preclinical Alzheimer's disease (AD) prevention studies is challenging. Online registries facilitate large scale prescreening of individuals at risk for AD to accelerate recruitment. APOE-prescreening has the potential to better identify at-risk individuals. This study investigated the feasibility and acceptability of at-home APOE-genotyping in cognitively-normal registrants of an online registry.

We invited 9,287 cognitively-normal registrants of Dutch Brain Research Registry (DBRR) aged 50 to 75 for at-home APOE-genotype testing, without receiving the results. Feasibility was measured by participation ratio (participation/interested), swab-return ratio (returned-swabs/participation), and genotyping-success ratio (analyzed swabs/returned swabs). Acceptability was measured with online questions about information provision and project scope. We explored prescreening questions potentially reducing screen-failures.

Feasibility was high with an 0.89 participation ratio (2,886/3,251), 0.90 swab-return ratio (2,886/2,597), 0.99 genotyping-success ratio (2,558/2,597). Acceptability was high, as participants were content with the information provision (87 %-97 %, n= 1,709–1,894), which was also well understood (91 %-93 %, n = 1,772–1,802). Among successful-analyzed swabs (n = 2,558), 27 % participants were APOE-ε4 heterozygote (n = 703), and 2 % homozygote (n = 60). Prescreening on a positive family history leads to a third reduction in the number of invitations needed to identify one APOE-ε4 carrier.

Our results suggest that APOE-ɛ4 genotyping in participants of an online research registry is feasible, well received and could be used to prescreen individuals at risk for AD for prevention studies. Adding a positive family history before invitation for APOE-genotyping, would further improve the prescreening process and reduce screen failures when identifying carriers.