Dilution testing using rapid diagnostic tests in a HIV diagnostic algorithm: a novel alternative for confirmation...

Area of Science:

• Infectious Diseases
• Public Health
• Biotechnology

Background:

• Current HIV testing in resource-limited settings omits confirmation tests due to cost, risking false positive diagnoses.
• A novel, low-cost dilution test is evaluated to improve HIV diagnostic accuracy.

Purpose of the Study:

• To assess the efficacy of a dilution test as a simple, rapid, and cost-effective method for confirming HIV diagnosis.
• To evaluate the dilution test's ability to differentiate true positives from false positives caused by cross-reacting antibodies.

Main Methods:

• The study involved 2895 participants in Ethiopia, using a tiebreaker algorithm for HIV diagnosis.
• Samples positive on initial screening, and 10% of negatives, were tested with the gold standard (Western Blot/PCR) and the dilution test using Determine™ RDT at various dilutions.
• The dilution test's performance was compared against the gold standard.

Main Results:

• The dilution test at a 1/160 dilution correctly identified 18 false positives from the RDT algorithm, with 99.6% sensitivity and 100% specificity.
• A single false negative result was observed at this dilution.
• Concordance between the gold standard and the 1/160 dilution was high at 99.8%.

Conclusions:

• The dilution test shows proof of concept as a supplementary, low-cost HIV confirmation method for resource-limited settings.
• Positive dilution tests can confirm HIV infection, while negative results may require nucleic acid testing to rule out false negatives.
• Further research is recommended to validate these findings in diverse settings.