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:

Objectives: We aimed to get insight into the effectiveness of phone calls 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 size 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:

In our sample size of n=200 per study, study 1, with a median time of 11 months since the last visit at the research site, had a response rate of 141 out of 200 participants (71%) while study 2, with a median duration of 55 months since the last visit, had a response rate of 100 out of 200 participants (50%) (P <.001). In study 1, 123 out of 200 contacted participants (62%) were answered directly by the participant while this was 72 out of contacted participants (36%) in study 2 (P=.003). 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). 141 out of 241 reached participants responded to the questionnaire. Of the 93 participants that had changed phone numbers, 50 participants (54%) had changed numbers because their phone was stolen. The most preferred method of being contacted was direct calling with 128 out of 141 participants naming this method followed by WhatsApp with 69 out of 141 participants.

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. Clinical Trial: Trial registration: The study was approved by the Research Ethics Committee of the University of Witwatersrand, Johannesburg, South-Africa (reference number M1811107).