Accuracy and Acceptability of the VISITECT CD4 Advanced Disease Test Compared With the PIMA CD4 Test at the Point of Care as Part of the Advanced HIV Disease Care Package: A Mixed-Methods Study

Background
CD4 testing is the first step of the advanced human immunodeficiency virus (HIV) disease (AHD) care package. The semiquantitative VISITECT CD4 Advanced Disease test (VISITECT; AccuBio) is increasingly used but has variable reported performance. We compared its diagnostic accuracy and acceptability with that of the PIMA CD4 test (PIMA; Abbott) at the point of care within the AHD care package.

Methods
A mixed-methods study was embedded in a community-based tuberculosis case-finding trial in South Africa. Following a VISITECT batch recall (April 2023), a sample of trial participants with HIV underwent VISITECT and PIMA testing in parallel on a single venous blood sample. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. We conducted in-depth-interviews with people with HIV (PWH), focus group discussions with nurses, and participant observations with nurse-PWH pairs.

Results
Among 609 included PWH, 76 (12.5%) were found to have CD4 cell counts ≤200/µL with VISITECT versus 28 (4.8%) with PIMA. The sensitivity, specificity, PPV, and NPV for VISITECT, compared with PIMA, were 89.3% (95% confidence interval, 71.8%–97.7%), 91.2% (95% CI, 88.6%–93.4%), 32.9% (95% CI, 22.5%–44.6%) and 99.4% (95% CI, 98.4%–99.9%), respectively. Three VISITECT results (0.05%) were false-negative (CD4 cell counts, 16/µL, 82/µL, 175/µL) and 51 (8.4%) were false-positive (median CD4 cell count, 563/µL [interquartile range, 382–739/µL]). PWH and public sector nurses believed that point-of-care CD4 tests improve access to CD4 cell counts. Study nurses preferred PIMA to VISITECT in terms of accuracy, duration, user-friendliness, and yielding of a numeric CD4 result.

Conclusions
Compared with PIMA, VISITECT had good diagnostic accuracy but low PPV and was less acceptable to study nurses. The role of VISITECT should be further evaluated.