JMIR Publications

ABSTRACT

Background:

Background:

Long term retention of research participants in studies is challenging. In research in Sub-Saharan Africa, phone calls are the most frequently used method to distantly engage with participants.

Objective:

Objective:

We aimed to get insight into the effectiveness of phone numbers and email to retain contact with participants and evaluated determinants of reachability.

Methods:

Method: A cross-sectional study was performed using the databases of two randomized controlled trials (RCTs) investigating different kinds of antiretroviral therapy (ART) in HIV-positive patients. One RCT finished in 2018 (study 1), the other finished in 2015 (study 2). A random sample of 200 participants per study was obtained. There were up to three phone numbers available per participant collected during the studies. Participants received a maximum of three phone calls on every available number on different days and at different times. Voicemails were left and emails sent wherever possible. We documented how many calls were answered, who answered, as well as after how many attempts participants were reached. To further increase our understanding of reachability we conducted a short questionnaire assessing factors contributing to reachability.

Results:

Results:

Study 1, with a median time of 11 months since the last visit at the research site, had a response rate of 71% (n=141/200) and study 2, with a median duration of 55 months since the last visit, had a response rate of 50% (n=100/200). In study 1, 62% (n=123/200) was answered by the participant while this was 36% (n=72/200) in study 2. The likelihood of reaching a participant decreased with time, odds ratio (OR) 0.73, 95% CI=0.63-0.84 for every year since the last face to face visit. Having more phone numbers per participant increased reachability (OR 2.32, 95% CI=1.24-4.36 for two phone numbers and OR 3.03, 95% CI=1.48-6.22 for three phone numbers compared to one number). Of all participants that responded to the questionnaire, 54% (n=50) had changed numbers because their phone was stolen. The most preferred method of being contacted was direct calling (55%, n=128) followed by WhatsApp (30%, n=69).

Conclusions:

Conclusion: Time since last visit and the number of phone numbers listed were the only determinants of reachability. Longer follow-up time is accompanied with a decrease in reachability by phone while more listed phone numbers increases the likelihood that someone can be reached. Each face to face contact with a participant should be used to verify and update the available phone numbers. WhatsApp or dedicated applications show promise to be used to get in contact with participants in addition to calling them. Clinical Trial: Trial registration: The study was approved by the Research Ethics Committee of the University of Witwatersrand, Johannesburg, South-Africa (reference number M1811107).