Personalized contact strategies and predictors of time to survey completion: analysis of two sequential randomized trials

Abstract

Background: Effective strategies for contacting and recruiting study participants are critical in conducting clinical research. In this study, we conducted two sequential randomized controlled trials of mail- and telephone-based strategies for contacting and recruiting participants, and evaluated participant-related variables' association with time to survey completion and survey completion rates. Subjects eligible for this study were survivors of acute lung injury who had been previously enrolled in a 12-month observational follow-up study evaluating their physical, cognitive and mental health outcomes, with their last study visit completed at a median of 34 months previously.

Methods: Eligible subjects were contacted to complete a new research survey as part of two randomized trials, initially using a randomized mail-based contact strategy, followed by a randomized telephone-based contact strategy for non-responders to the mail strategy. Both strategies focused on using either a personalized versus a generic approach. In addition, 18 potentially relevant subject-related variables (e.g., demographics, last known physical and mental health status) were evaluated for association with time to survey completion.

Results: Of 308 eligible subjects, 67% completed the survey with a median (IQR) of 3 (2, 5) contact attempts required. There was no significant difference in the time to survey completion for either randomized trial of mail- or phone-based contact strategy. Among all subject-related variables, age ≤40 years and minority race were independently associated with a longer time to survey completion.

Conclusion: We found that age ≤40 years and minority race were associated with a longer time to survey completion, but personalized versus generic approaches to mail- and telephone-based contact strategies had no significant effect. Repeating both mail and telephone contact attempts was important for increasing survey completion rate.

Trial registration: NCT00719446.

Figure 1

CONSORT flow diagram for mail trial. Mail survey completion rate: (81 + 67) respondents/(157 + 147) potential respondents = 49%.

Figure 2

CONSORT flow diagram for phone trial. Telephone survey completion rate: [(19 + 16) respondents + (11 + 12) answered telephone on first call]/(55 + 58) potential respondents = 51%. ¹ Excluded from analysis of randomized trial of telephone messages, but censored in analysis of the entire cohort. ² Included in calculation of survey completion rate, but excluded from Cox models.

Figure 3

Estimated proportions of participants remaining to be contacted over time. These 3 panels display the survival function for time to survey completion since randomization for the mail- and telephone-based randomized trials. Panel A displays the overall survival function for all participants participating in the trials. Panels B and C display the survival function for the mail and telephone randomized trials, respectively.