Publications & Reports

The field performance and diagnostic accuracy of a low-cost instrument-free point-of-care CD4 test (VISITECT(R) CD4) performed by different health worker cadres among pregnant women.

Luchters S, Technau K, Mohamed Y, Chersich MF, Agius PA, Pham MD, Garcia ML, Forbes J, Shepherd A, Coovadia A, Crowe SM, Anderson DA
Burnet Institute, 85 Commercial Road, Melbourne, VIC 3004, Australia Stanley.luchters@burnet.edu.au.

Abstract

BACKGROUND: Measuring CD4 counts remains an important component of HIV care. The VISITECT® CD4 is the first-ever instrument-free low-cost point-of-care CD4 test with results interpreted visually after 40 minutes, providing a result of above or below 350 CD4 cells/mm(3). METHODS: Field performance and diagnostic accuracy of the test was assessed among HIV-infected pregnant women in South Africa. A nurse performed testing at the point-of-care using both venous and finger-prick blood, and a counsellor and laboratory staff tested venous blood in the clinic laboratory (four VISITECT® CD4 tests/participant). Performance was compared to the mean CD4 count from duplicate flow cytometry tests on venous blood (FACSCalibur Trucount). FINDINGS: In 2017, 156 patients were enrolled, providing a total of 624 VISITECT® CD4 tests (468 venous and 156 finger-prick samples). Of 624 tests, 28 (4.5%) were inconclusive. Generalised Linear Mixed Modelling showed better performance of the test on venous blood (sensitivity=81.7%, 95%CI=72.3-91.1; and specificity=82.6%, 95%CI=77.1-88.1) than on finger-prick specimens (sensitivity=60.7%, 95%CI=45.0-76.3; and specificity=89.5%, 95%CI=83.2-95.8; p=0.001). No difference in performance was detected by cadre of health worker (p=0.113) or between point-of-care versus laboratory-based testing (p=0.108). CONCLUSIONS: Adequate performance of VISITECT® CD4 with different operators and at the point-of-care, and no need of electricity or instrument, shows the potential utility of this device, especially for facilitating decentralization of CD4 testing services in rural areas.

Link to publisher’s web site

FUNDING: Funding was provided by the Saving Lives at Birth partners and the Australian NHMRC Project Grant GNT1063725.