Diagnostic performance and usability of the VISITECT® CD4 Advanced Disease semiquantitative test for advanced HIV disease screening
In sub-Saharan Africa, a third of people starting antiretroviral therapy and majority of patients returning to HIV-care after disengagement, present with Advanced HIV Disease (ADH), and are at high risk of mortality. Simplified and more affordable point-of-care (POC) diagnostics are required to increase access to prompt CD4 cell count screening for ambulatory and asymptomatic patients. The VISITECT®CD4 Lateral Flow Assay (LFA) is a disposable POC test, providing a visually interpreted result of above or below 200 CD4 cells/mm3.
This study evaluated the diagnostic performance of VISITECT® CD4 Advanced Disease test for venous and fingerstick sampling. The study enrolled consenting patients above 18 years of age and eligible for CD4 testing in Nsanje district hospital (Malawi), Gutu mission hospital (Zimbabwe) and Centre hopitalier de Kabinda (DRC). A total of 708 venous blood samples were tested with VISITECT® test and in comparison with the BD FACSCount assay as reference test method, in the laboratories (Phase 1) to determine diagnostic accuracy.
A total of 433 finger-prick (FP)/fingerstick samples were tested on the index test at POC by clinicians (Phase 2). The study measure the usability of this test using a self-completed questionnaire administered to all testers.
The results shows sensitivity of the VISITECT® CD4 LFA using venous blood in the laboratory was 95.0% and specificity was 81.9%. Using FP samples, the sensitivity of the VISITECT® CD4 LFA was 98.3% [and specificity was 77.2%. Usability of the VISITECT® CD4 LFA was high across the study sites with 97% successfully completed tests.
VISITECT® CD4 LFA is a promising test for decentralized CD4 screening in resource-limited settings, without access to CD4 testing and and it can trigger prompt management of patients with AHD. Lay health cadres should be considered to conduct VISITECT® CD4 LFA testing in PHCs as well as coordinating all other POC quality assurance.