AUTHOR=Klee Bianca , Costa Daniela , Frese Thomas , Knoechelmann Anja , Meyer Gabriele , Meyer Thorsten , Purschke Oliver , Schildmann Jan , Steckelberg Anke , Mikolajczyk Rafael 

TITLE=To Remind or Not to Remind During Recruitment? An Analysis of an Online Panel in Germany

JOURNAL=International Journal of Public Health

VOLUME=Volume 69 - 2024

YEAR=2024

URL=https://www.ssph-journal.org/journals/international-journal-of-public-health/articles/10.3389/ijph.2024.1606770

DOI=10.3389/ijph.2024.1606770

ISSN=1661-8564

ABSTRACT=To explore the role of reminders on the recruitment and continued participation in an online panel.

50,045 individuals from five German federal states were invited by regular mail to participate in the online “Health Related Beliefs and Health Care Experiences in Germany” study. Those, who did not respond to the first attempt, received one postal reminder. Comparisons of sociodemographic characteristics and responses were performed between first-attempt responders and those who enrolled after second letter.

After the initial letter, 2,216 (4.4%, 95%CI: 4.3-4.6%) registered for the study; after a reminder  1,130 (2.5%, 2.3-2.6% of those reminded) enrolled. Minor sociodemographic differences were observed between the groups and the content of the responses did not differ. Second-attempt responders were less likely to participate in subsequent questionnaires: 67.3% of first-attempt vs 43.3% second-attempt responders participated  in their fourth survey. Recruitment costs were 79% higher for second-attempt responders.  

While reminders increased the number of participants, lower cost-effectiveness and a higher attrition of second-attempt responders support the use of single invitation only for studies with a similar design to ours, when the overall participation is low.