Performance Characteristics Of An Instrument-Free Point-Of-Care Cd4 Test (Visitect (R) Cd4) For Use In Resource-Limited Settings

Objective: CD4+ T lymphocyte count remains the most common biomarker of immune status and disease progression in human immunodeficiency virus (HIV)-positive individuals. VISITECT (R) CD4 is an instrument-free, low-cost point-of-care CD4 test with a cut-off of 350 CD4 cells/mu L. This study aimed to evaluate VISITECT (R) CD4 test's diagnostic accuracy.Methods: Two hundred HIV-positive patients attending a tertiary HIV centre in South India were recruited. Patients provided venous blood for reference and VISITECT (R) CD4 tests. An additional finger-prick blood sample was obtained for VISITECT (R) CD4. VISITECT (R) CD4's diagnostic performance in identifying individuals with CD4 counts <= 350 cells/mu L was assessed by calculating sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) taking flow cytometry as the reference.Results: The overall agreement between VISITECT (R) CD4 and flow cytometry was 89.5% using venous blood and 81.5% using finger-prick blood. VISITECT (R) CD4 showed better performance using venous blood [sensitivity: 96.6% (95% confidence interval: 92.1%-98.9%), specificity: 70.9% (57.1%-82.4%), PPV: 89.7% (83.9%-94.0%) and NPV: 88.6% (75.4%-96.2%)] than using finger-prick blood [sensitivity: 84.8% (77.9%-90.2%), specificity: 72.7% (59.0%-83.9%), PPV: 89.1% (82.7%-93.8%) and NPV: 64.5% (51.3%-76.3%)].Conclusion: VISITECT (R) CD4 performed well using venous blood, demonstrating its potential utility in decentralization of CD4 testing services in resource-constrained settings.