Usability and acceptability of capillary blood self-collection devices among adults living with HIV in Zambia: a randomized crossover trial

Abstract Introduction HIV viral load (VL) monitoring is essential for evaluating antiretroviral treatment effectiveness, but reliance on venepuncture in high-burden settings can delay sample collection and return of results. Self-collection blood devices could enable pre-appointment collection, reduce clinic visits, and improve timeliness. We evaluated the usability of two devices, Tasso+ and Collect2Know v1.0 (C2K), among people living with HIV in Zambia. Methods An individually randomized crossover trial was conducted with 70 adults living with HIV receiving ART and attending routine monitoring visits (October–December 2024). Participant’s used each device in a randomized order, with supervision for the first use of each device and a second, unsupervised home collection one week later. Success was defined as self-collection of ≥0.5 mL of blood during unsupervised use. A questionnaire assessed device usability and participant’s experiences relative to standard venepuncture, complemented by qualitative findings from the formative phase and trial. Results Of 63 participants completing the study (35.5% male, 64.5% female, aged 18–50+), 85.7% (54/63) successfully collected ≥ 0.5 mL with Tasso+, compared to 38.1% (24/63) with C2K (McNemar test, p < 0.001; OR 10.99, 95% CI: 3.45–56.06). Among participants who successfully collected a sample using the Tasso+ device, 61.1% (33/54) failed to achieve successful collection with the C2K v1.0 device. Healthcare workers highlighted reduced clinic congestion as a key benefit of self-sampling, while patients cited less pain, reduced fear, and improved privacy as significant advantages. Conclusion This randomized crossover trial found that Tasso+ had greater collection success and was easier and more acceptable to use than C2K v1.0 among adults living with HIV. The findings demonstrate that participants could independently collect and return the prespecified volume of capillary blood; however, they do not establish whether these specimens are suitable for HIV viral load testing. Further studies comparing device-collected capillary blood with standard venous plasma are needed to evaluate analytical performance across clinically relevant viral load ranges. Trial Registration The study was registered with the Pan African Clinical Trial Registry (PACTR202605883649675) on 24 February 2024.