An analysis of the predictive value of the HIV Ag/Ab screening assay within the performance characteristics of the DiaSorin LIAISON XL for the detection of blood-borne viruses

•LIAISON XL correlates well to the ARCHITECT for detection of blood-borne viruses.•The PPV of HIV screening can be ameliorated by increasing the cutoff of Ab testing.•The sensitivity of HIV Ab testing is not affected by increasing the cutoff to 4. Correct identification of blood borne viral infections, such as hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) is crucial in detection and follow up of infection in patients. We evaluated the diagnostic performance of the DiaSorin LIAISON XL (LIAISON XL) for screening of HBV, HCV and HIV infection. In addition, we investigated the variability of the signal-to-cuttoff ratio (S/CO) of the LIAISON XL HIV Ag/Ab assay and it’s predictive value in subsequent confirmation of HIV-1 infection. We analyzed 16,497 blood samples on which HBV, HCV and HIV screening was performed. We defined A) archived samples previously tested with an arbitrary result in the Abbott ARCHITECT i2000SR system; B) prospectively collected samples which were simultaneously tested on the LIAISON XL and ARCHITECT i2000SR; C) prospectively collected serum samples for HIV testing which were tested solely on the LIAISON XL. The agreements of HBV-, HCV-, and HIV markers between the two compared systems are remarkably high. Among the samples which were prospectively tested for HIV Ab/Ag on the LIASON XL, 229 (1.6%) were reactive of which 141 (61.6%) could be confirmed. Increasing the signal-to-cutoff value to 4 could increase the positive predictive value (PPV) to 88.1% without decreasing sensitivity. The LIAISON XL system proved to be an excellent system for diagnosing HBV, HCV, and HIV. Our data for the first time showed that increasing the HIV S/CO ratio was safe and increased the PPV for confirmed HIV infection in the tested population.