The impact of phone calls on follow-up rates in an online depression prevention study

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Background Automated Internet intervention studies have generally had large dropout rates for follow-up assessments. Live phone follow-ups have been often used to increase follow-up completion rates. Objective To compare, via a randomized study, whether receiving phone calls improves follow-up rates beyond email reminders and financial incentives in a depression prevention study. Method A sample of 95 participants (63 English-speakers and 32 Spanish-speakers) was recruited online to participate in a “Healthy Mood” study. Consented participants were randomized to either a Call or a No Call condition. All participants were sent up to three email reminders in one week at 1, 3, and 6 months after consent, and all participants received monetary incentives to complete the surveys. Those in the Call condition received up to ten follow-up phone calls if they did not complete the surveys in response to email reminders. Results The follow-up rates for Call vs. No Call conditions at 1, 3, and 6 months, respectively, were as follows: English speakers, 58.6% vs. 52.9%, 62.1% vs. 52.9%, and 68.9% vs. 47.1%; Spanish speakers, 50.0% vs. 35.7%, 33.3% vs. 21.4%, and 33.3% vs. 7.1%. The number of participants who completed follow-up assessments only after being called at 1-, 3- and 6 months was 2 (14.3%), 0 (0%), and 3 (25.0%) for English speakers, and 2 (18.9%), 0 (0%), and 1 (7.7%) for Spanish speakers. The number of phone calls made to achieve one completed follow-up was 58.8 in the English sample and 57.7 and Spanish-speaking sample. Conclusions Adding phone call contacts to email reminders and monetary incentives did increase follow-up rates. However, the rate of response to follow-up was low and the number of phone calls required to achieve one completed follow-up raises concerns about the utility of adding phone calls. We also discuss difficulties with using financial incentives and their implications.




Muñoz, R. F., Leykin, Y., Barrera, A. Z., Brown, C. H., & Bunge, E. L. (2017). The impact of phone calls on follow-up rates in an online depression prevention study. Internet Interventions, 8, 10–14.

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