Background: Traditionally, clinical studies rely on brick-and-mortar sites to recruit participants. Newer technology-based studies have utilized non-traditional virtual methods that can potentially recruit more diverse populations and shorten recruitment timelines. This manuscript aims to quantify how sample metrics across three virtual studies compare to traditionally recruited samples, as a first step in building an empirical evidence base for the experience of participant recruitment in virtual studies.
Methods: We conducted a systematic search of the literature using PubMed to identify relevant studies conducted in the United States in cognitive health, diabetes, and hypertension (which we called comparator studies) to compare to three virtual studies. For each included study, we extracted participant demographic characteristics and information on recruitment methods and timing. Two investigators independently extracted this data, compared results for consistency, and contacted comparator study authors for clarifications. Characteristics for measurement included age, sex, race/ethnicity, states represented, recruitment time, and recruitment rate.
Results: We identified 19 comparator studies. Virtually recruited samples were slightly younger, had more female participants, and were split on enrollment of racial minorities as compared to comparator studies. Virtually recruited samples were more diverse geographically and recruited faster.
Conclusions: Virtual recruitment may enhance efficiency and enable more individuals to participate in clinical research. To our knowledge, this is the first rigorous and replicable study comparing participant demographic characteristics and recruitment metrics between virtual and traditional recruitment methodologies. Future research should compare a wider range of studies on other metrics such as overall cost of recruitment and quality of participants.