Performance of an Alternative Laboratory-Based HIV Diagnostic Testing Algorithm Using HIV-1 RNA Viral Load

Area of Science:

• Clinical diagnostics
• Virology
• Public health

Background:

• The current US standard for laboratory diagnosis of HIV infection involves an HIV-1/2 antigen/antibody (Ag/Ab) immunoassay, followed by an HIV-1/2 antibody (Ab) differentiation test.
• A supplemental HIV-1 nucleic acid test is used to resolve indeterminate or discordant results.

Purpose of the Study:

• To compare the performance of a novel 3-step diagnostic algorithm with the current recommended algorithm for HIV infection.
• To evaluate an alternative algorithm utilizing HIV viral load quantification for improved diagnostic efficiency.

Main Methods:

• A 3-step alternative algorithm was compared to the standard algorithm using stored specimens from individuals seeking HIV testing.
• The alternative algorithm included an Ag/Ab test, an HIV-1 RNA viral load assay, and an Ab differentiation test if viral load was undetectable.
• Sensitivity, specificity, and correct classification rates were calculated for both algorithms across different infection stages.

Main Results:

• All tested Ag/Ab assays demonstrated comparable sensitivity and specificity.
• The alternative algorithm, incorporating viral load testing, accurately classified specimens from early HIV infection and false-reactive screening results.
• The majority of specimens from established HIV infections were also correctly classified by the alternative algorithm.

Conclusions:

• An alternative HIV diagnostic algorithm using viral load quantification shows promise for streamlining diagnosis.
• This approach has the potential to reduce the total number of tests performed and shorten diagnostic turnaround times.
• Considerations for implementation include cost, regulatory approval, test availability, and differentiating early from established infections.