Assessing the Response Results of an mHealth-Based Patient Experience Survey Among People Receiving HIV Care in Lusaka, Zambia: Cohort Study
Authors: Mutale Jacob , Sikombe Kombatende , Mwale Boroma , Lumpa Mwansa , Simbeza Sandra , Bukankala Chama , Mukamba Njekwa , Mody Aaloke , Beres Laura K , Holmes Charles B , Bolton Moore Carolyn , Geng Elvin H , Sikazwe Izukanji , Pry Jake M 
Published: June 2024

Background
This pilot study evaluates the effectiveness of mobile talk-time incentives in maintaining participation in a longitudinal mobile health (mHealth) data collection program among people living with HIV in Lusaka, Zambia. While mHealth tools, such as mobile phone surveys, provide vital health feedback, optimal incentive strategies to ensure long-term engagement remain limited. This study explores how different incentive levels affect response rates in multiple survey rounds, providing insights into effective methods for encouraging ongoing participation, especially in the context of Zambia’s prepaid mobile system and multi-SIM usage, a common practice in sub-Saharan Africa.

Objective
This study aimed to assess the response rate success across multiple invitations to participate in a care experience survey using a mobile phone short codes and unstructured supplementary service data (USSD) model among individuals in an HIV care setting in the Lusaka, Zambia.

Methods
Participants were recruited from 2 study clinics–1 in a periurban setting and 1 in an urban setting. A total of 2 rounds of survey invitations were sent to study participants on a 3-month interval between November 1, 2018, and September 23, 2019. Overall, 3 incentive levels were randomly assigned by participant and survey round: (1) no incentive, (2) 2 Zambian Kwacha (ZMW; US $0.16), and (3) 5 ZMW (US $0.42). Survey response rates were analyzed using mixed-effects Poisson regression, adjusting for individual- and facility-level factors. Probability plots for survey completion were generated based on language, incentive level, and survey round. We projected the cost per additional response for different incentive levels.

Results
A total of 1006 participants were enrolled, with 72.3% (727/1006) from the urban HIV care facility and 62.4% (628/1006) requesting the survey in English. We sent a total of 1992 survey invitations for both rounds. Overall, survey completion across both surveys was 32.1% (637/1992), with significantly different survey completion between the first (40.5%, 95% CI 37.4-43.6%) and second (23.7%, 95% CI 21.1-26.4) invitations. Implementing a 5 ZMW (US $0.42) incentive significantly increased the adjusted prevalence ratio (aPR) for survey completion compared with those that received no incentive (aPR 1.35, 95% CI 1.11-1.63). The cost per additional response was highest at 5 ZMW, equivalent to US $0.42 (72.8 ZMW [US $5.82] per 1% increase in response).

Conclusions
We observed a sharp decline of almost 50% in survey completion success from the initial invitation to follow-up survey administered 3 months later. This substantial decrease suggests that longitudinal data collection potential for a care experience survey may be limited without additional sensitization and, potentially, added survey reminders. Implementing a moderate incentive increased response rates to our health care experience survey. Tailoring survey strategies to accommodate language preferences and providing moderate incentives can optimize response rates in Zambia.

Trial Registration
Pan African Clinical Trial Registry PACTR202101847907585; https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=14613