Usability of HIV-1 Assay Using DBS for Early Infant Diagnosis in Field Settings in Kenya

The Xpert HIV-1 Qualitative assay has been in use in Kenya since 2016 for infant diagnosis of HIV. Recently, the assay has been improved and its impact of this on ease of use is yet to be determined. We sought to determine the usability of Xpert® HIV-1 Qual XC assay using dried blood spots (DBS) for early infant diagnosis following this improvement.

This was a cross-sectional usability study undertaken in 2 selected health facilities in Kenya from October 2020 to February 2021. The laboratory technicians were retrained for this study. HIV-exposed infants were recruited with the consent of their parents. Patient data were recorded, and DBS samples were collected from the infants and tested for HIV on the improved assay. Each laboratory technician performing the assay documented usability characteristics on the provided questionnaire. Data on test errors were collected from the machine logs and analyzed using STATA for Windows.

Of 313 test cartridges, 265 (84.66%) were successfully tested on the GeneXpert platform, and 263 valid outcomes were used for comparison with the Roche CAP/CTM HIV-1 Qualitative assay. The sensitivity, specificity, and accuracy of the Xpert HIV-1 Qualitative assay on DBS was 100%. Overall, 48 (15.34%) errors were recorded; 40 (83.33%) were user related and 8 (16.67%) were hardware related. All 4 (4/4, 100%) participating laboratory technicians said the assay had a simple workflow, was easy to use, the tests results were easy to interpret, and the assay throughput was sufficient for their workload.

The improved Xpert HIV-1 Qual XC assay is highly accurate, has a simple workflow, and is easy to use and easy to interpret. Both hardware- and user- related errors are common.