Usability and acceptability of a novel TB infection diagnostic test among key populations in Mexicali

Tuberculin skin test (TST) remains the standard-of-care test for TB infection in many high TB-burden settings. Despite existing diagnostics overcoming challenges associated with TST implementation, there has been poor uptake programmatically. We conducted formative research into patients' and providers' perceptions of acceptability and usability of a novel IGRA test, called QIAreach QuantiFERON TB (or, QIAreach), compared to TST in a programmatic setting in Mexicali. Programmatic outreach to screen for TB disease and infection was conducted in Mexicali (December 2020-July 2021). A 5-point Likert scale survey was administered to two groups at high risk of TB infection-people who use drugs (PWUD) and household contacts (HHC) of TB patients-and who received testing via TST and QIAreach. This survey evaluated patients' comparative preferences for the two tests. Additionally, a modified system usability scale was administered to TB program staff involved in the administration and processing of TST and IGRA tests pre- and post-QIAreach implementation to measure the tests' perceived usability. Of 201 patients, 103 (51.2%) were PWUD and 98 (48.8%) were HHCs. The acceptability survey found that the blood draw for QIAreach was preferred to, and more trustworthy than, the injection for TST. Also, only requiring one visit with providers for QIAreach was preferred among HHCs, but comparatively less preferable for PWUD. In-person delivery of test results was preferable and more trustworthy. The majority preferred QIAreach over TST; though this was higher among PWUD. Nine staff completed the usability survey. Perceived usability before implementing the IGRA remained nearly constant from the pre-implementation timepoint (SUS Score: 52.5, IQR: 45-65) to the post-implementation timepoint (50, IQR: 45-52.5, p = 0.31). IGRA was more acceptable to patients, and perceived usability was mixed among staff. Patient and provider preferences must be considered when integrating novel IGRA tests into settings where TST is routinely used.