Impact of financial compensation on enrollment and participation in a remote, mobile-app based research study

Abstract

Background: There is no consensus on how to determine appropriate financial compensation for research recruitment. Selecting incentive amounts that are reasonable and respectful, without undue inducement, remains challenging. Previously, we demonstrated that incentive amount significantly impacts participants' willingness to complete various hypothetical research activities. Here we further explore this relationship in a mock decentralized study.

Methods: Adult ResearchMatch volunteers were invited to join a prospective study where interested individuals were given an opportunity to view details for a study along with participation requirements, then offered a randomly generated compensation amount between $0 and $50 to enroll and participate. Individuals agreeing to participate were then asked to complete tasks using a remote mobile application (MyCap), for two weeks. Tasks included a weekly survey, a daily gratitude journal and daily phone tapping task.

Results: Willingness to participate was 85% across all incentive levels but not significantly impacted by amount. Task completion appeared to increase as a function of compensation until a plateau at $25. While participants described the study as low burden and reported that compensation was moderately important to their decision to join, only 31% completed all study tasks.

Conclusion: While offering compensation in this study did not have a strong effect on enrollment rate, this work provides insight into participant motivation when joining and participating in studies employing mobile applications.

Keywords: Clinical trials; financial incentive; motivation; participant compensation; participant recruitment.

Figure 1.

Participant flow for the study. (A) Schematic showing participant experience from invitation to study completion. The random compensation offer was generated after participant demographics were collected (dotted box outline) and was shown to volunteers at the same time as the study description. (B) Enrollment flow from invitation to enrollment and downloading the study app, MyCap.

Figure 2.

Participant enrollment and adherence to mock study tasks. (A) Rate of participant enrollment in the study with the line representing the Loess curve for rate of enrollment by promised compensation amount for the whole study group. Dots are mean values at each promised compensation amount, and bars are 95% Wilson confidence intervals. n = 486 (as enrollment rate was calculated from those who said yes OR no). (B) Mean task completion; red line representing the Loess curve of total task completion by compensation amount, n = 286. Bars depicting the 95% Wilson confidence interval. (C) Proportion of participants that did or did not complete ALL study tasks for each promised compensation amount, n = 286.

Figure 3.

Participant experience survey responses. (A) Box and whisker plot for responses around perceived study burden and importance of compensation when joining this study, n = 265. (B) Box and whisker plot of compensation amounts suggested by participants that believed their initial compensation offer was unfair, n = 13 (3 respondents did not provide a suggested compensation amount). Dots are individual response values. (C) Additional reasons participants chose to be in this study (participants could select more than one answer when responding), n = 265.

Figure 4.

Reasons for study declination by participants. (A) Responses to the question “Would you please share any reasons why you didn't want to join the study?” from respondents that turned down the study, n = 50. Respondents could select all options that applied to them. (B) Compensation amount suggestions from respondents that believed their compensation offer was not high enough, n = 19.