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

TL;DR

A study compared two CD4 tests for HIV disease care in South Africa, finding that while VISITECT had good accuracy, it was less preferred by nurses due to lower reliability and usability.

Contribution

This study evaluates the diagnostic accuracy and acceptability of the VISITECT CD4 test compared to the PIMA CD4 test in a real-world HIV care setting.

Findings

VISITECT had 89.3% sensitivity and 91.2% specificity compared to PIMA.

VISITECT had a low positive predictive value (32.9%) and 8.4% false-positive results.

Study nurses preferred PIMA over VISITECT for accuracy and usability.

Abstract

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.

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.

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.

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.

The VISITECT CD4 Advanced Disease test had good sensitivity and specificity but low positive predictive value compared with the PIMA CD4 test, when performed at the point of care in the community, within an advanced human immunodeficiency virus care package. Study nurses preferred PIMA to VISITECT.

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