Usability and Acceptability of Capillary Blood Self-Collection Devices among Adults Living with HIV in Zambia: A Randomized Crossover Trial

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. Emerging approaches suggest that lower blood volumes may be sufficient for VL and drug resistance testing using novel methods such as the next-generation sequencing platform, although these remain under evaluation. Self-sampling 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 stable PLHIV attending routine ART visits (October–December 2024). Participants used each device in a randomized order, with supervision for the first use of each device and a second, unsupervised home sampling one week later. Success was defined as self-collection of ≥ 0.5 mL of blood during unsupervised use. A questionnaire captured perceptions of device usability, compared to standard venepuncture options, and was complemented by findings from qualitative research conducted during both the formative and during the trial. Results Of 63 participants completing the study (35.5% male, 64.5% female, aged 18–50+), 87.1% (54/63) successfully collected ≥ 0.5 mL with Tasso+, compared to 37.1% (24/63) with C2K (McNemar test, p <0.001; OR 11.45, 95% CI: 4.83–27.10). 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 (Table 1) 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 crossover RCT demonstrated that device-assisted, minimally invasive sampling offers high usability for self-collection among PLHIV. The adoption of such patient-led technologies could streamline HIV monitoring, enhance patient experience, and enable timely detection of treatment failure. Further exploration of minimally invasive sampling devices, including optimisation of device design and cost, is warranted in broader real-world contexts. Trial Registration Pan African Clinical Trial Registry PACTR202605883649675, registered on 24 February 2024.