Technical Performance Evaluation of the MyT4 Point of Care Technology for CD4+ T Cell Enumeration

Abstract

ObjectiveThough absolute CD4+ T cell enumeration is the primary gateway to antiretroviral therapy initiation for HIV-positive patients in all developing countries, patient access to this critical diagnostic test is relatively poor. We technically evaluated the performance of a newly developed point-of-care CD4+ T cell technology, the MyT4, compared with conventional CD4+ T cell testing technologies.DesignOver 250 HIV-positive patients were consecutively enrolled and their blood tested on the MyT4, BD FACSCalibur, and BD FACSCount.ResultsCompared with the BD FACSCount, the MyT4 had an r2 of 0.7269 and a mean bias of −23.37 cells/µl. Compared with the BD FACSCalibur, the MyT4 had an r2 of 0.5825 and a mean bias of −46.58 cells/µl. Kenya currently uses a CD4+ T cell test threshold of 350 cells/µl to determine patient eligibility for antiretroviral therapy. At this threshold, the MyT4 had a sensitivity of 95.3% (95% CI: 88.4–98.7%) and a specificity of 87.9% (95% CI: 82.3–92.3%) compared with the BD FACSCount and sensitivity and specificity of 88.2% (95% CI: 79.4–94.2%) and 84.2% (95% CI: 78.2–89.2%), respectively, compared with the BD FACSCalibur. Finally, the MyT4 had a coefficient of variation of 12.80% compared with 14.03% for the BD FACSCalibur.ConclusionsWe conclude that the MyT4 performed well at the current 350 cells/µl ART initiation eligibility threshold when used by lower cadres of health care facility staff in rural clinics compared to conventional CD4+ T cell technologies.

Performance Evaluation of the MyT4 Technology for Determining ART Eligibility

“…Although samples were not tested in the intended setting of lower level health care facilities by nurses, other studies observed that the performance by either laboratory technicians or nurses using POC CD4 technologies was similar [16, 17, 22, 23]. A recent study of the MyT4 evaluation in the intended field setting using finger-prick blood also highlighted comparable performance to conventional technologies [17].…”

“…In the same study, Mwau et al . observed that formal microscopy skills were not necessary for successful testing and result interpretation [17]. Further studies would be critical to understand the performance of the MyT4 technology in the intended field setting by the intended end users.…”

“…A sedimentation stage follows, during which the heavy CD4 + T-cells stack in the tube inside the bottom of the test cartridge. The stack height is then read visually using a built-in lens with a calibrated ruler [17, 18]. …”

“…The simplicity, rapid results, and lack of infrastructure requirements of POC technologies allows for significant decentralization of the CD4 testing network beyond reference laboratories [14]. Previously available POC CD4 technologies have been successfully technically evaluated [15–17] and showed significant positive patient impact [12, 13]. For optimal utilization and reliable testing, it is critical to monitor such a decentralized network to ensure consistently high quality testing.…”

Advances in biosensing strategies for HIV-1 detection, diagnosis, and therapeutic monitoring

“…After centrifuging the particles and cells the height of the pellet was measured for the quantification of CD4 + T cells. This technique had a sensitivity of 95% and specificity of 87% at the threshold of 350 cells/μL [108]. There is also a microfluidics-based mChip technology (mobile microfluidic chip for immunoassay on protein markers) that has been used to detect HIV-1 and only requires 1 microliter of unprocessed whole blood [109].…”