JMIR Publications

ABSTRACT

Background:

Web- or app-based digital studies allow for more efficient collection of health data for research. However, remote recruitment into digital studies can enroll non-representative study samples, which hinders the robustness and generalizability of findings. Through the systematic evaluation of an email-based campaign on recruitment into the Health eHeart Study, we aim to uncover key sociodemographic and clinical factors that contribute to enrollment.

Objective:

This study sought to understand factors related to participation in the Health eHeart Study as a result of a large-scale remote email recruitment campaign.

Methods:

We conducted a cohort analysis on all invited UCSF patients to identify sociodemographic and clinical predictors of enrollment into the Health eHeart Study. The primary outcome was enrollment, defined by account registration and consent into the Health eHeart Study. The email recruitment campaign was carried out from August 2015 to February 2016, with electronic health record data extracted between September 2019 to December 2019.

Results:

The email recruitment campaign delivered at least one email invitation to 93.5% (193,606/206,983) of all invited patients, and yielded a 3.6% (7,012/193,606) registration rate among contacted patients and an 84.1% (5,899/7,012) consent rate among registered patients. Adjusted multivariate logistic regression models analyzed independent sociodemographic and clinical predictors of (1) registration among contacted participants and (2) consent among registered participants. Odds of registration were higher among patients who are older, women, White/non-Hispanic, active patients with commercial insurance or Medicare, with a higher comorbidity burden, with congenital heart failure, and randomized to receive up to two recruitment emails. Patterns of subsequent consent after initial registration were somewhat different, with opposite trends by age and gender. However, odds of consent remained higher among patients who were White/non-Hispanic and those with commercial insurance.

Conclusions:

This study provides important insights into the potential returns on participation when digital study teams invest resources in using email for recruitment. Findings show that participant enrollment was driven more strongly by sociodemographic than clinical factors. Overall, email is an extremely efficient means of recruiting participants from a large list into the Health eHeart Study. Despite some improvements in representation, the formulation of truly diverse studies will require additional resources and strategies to overcome persistent participation barriers.