Specificity of two HIV screening tests detecting simultaneously HIV-1 p24 antigen and antibodies to HIV-1 and -2.
This study aimed at assessing the specificity of the Elecsys® HIV combi PT in comparison to the ARCHITECT® HIV Ag/Ab Combo. With both of these assays, 3997 unselected sera from patients of a tertiary health care centre in Basel, Switzerland, were screened for HIV. Reactive sera were reanalysed on the VIDAS® HIV Duo Ultra to identify false-reactive specimens prior to confirmation by quantitative PCR and line immunoassay. The Elecsys® compared to the ARCHITECT® shows a similar specificity (99.7% versus 99.8%) but a slightly lower positive predictive value (71.8% versus 80%). Samples tested with a cut-off index (COI) between 0.91 and 4.85 (cut-off <0.9) with the Elecsys® and with a signal to cut-off index (S/CO) between 1.09 and 12.49 (cut-off <1.0) with the ARCHITECT® were false-reactive. There was no false-reactive result with the VIDAS®. Of the false-reactive samples, 66.7% could be related to patient-specific underlying conditions. The HIV two-tiered diagnostic algorithm proposed in this work improved the positive predictive values of the Elecsys® or ARCHITECT® to 100% when the results of the VIDAS® were included. Values just above the cut-off are highly suspicious to be false-reactive and high COI or S/CO ratios are associated with true positivity.
['Blaich|Annette|A|', 'Buser|Andreas|A|', 'Stöckle|Marcel|M|', 'Gehringer|Christian|C|', 'Hirsch|Hans H|HH|', 'Battegay|Manuel|M|', 'Klimkait|Thomas|T|', 'Frei|Reno|R|']
D015492:AIDS Serodiagnosis D000328:Adult D005189:False Positive Reactions D005260:Female D015483:HIV Antibodies D016655:HIV Core Protein p24 D015658:HIV Infections D015497:HIV-1 D015498:HIV-2 D006801:Humans D007118:Immunoassay D008297:Male D011237:Predictive Value of Tests D012367:RNA, Viral D011933:Reagent Kits, Diagnostic D012680:Sensitivity and Specificity
Specificity HIV False reactive results Fourth generation immunoassays