TABLE 2.

Performance of the Architect HIV Ag/Ab combination assay according to cutoff S/CO ratios

ParameterValue(s) based on cutoff S/CO ratio
Value of cutoff S/CO ratio1.06.68.8
No. of positive initial screening test results (%)543 (0.350)216 (0.139)209 (0.135)
    No. of false-positive results (%)346 (0.223)19 (0.012)13 (0.012)
    No. of indeterminate results (%)4 (0.003)4 (0.003)4 (0.003)
    No. of true HIV-positive results (%)157 (0.101)157 (0.101)156 (0.100)
    No. of previously confirmed HIV-positive results (%)36 (0.023)36 (0.023)36 (0.023)
Specificity (%)100.00100.0099.36
    95% confidence interval (%)97.02-100.0097.02-100.0095.97-99.97
Positive predictive value (%)99.7899.9999.99
    95% confidence interval (%)99.75-99.8099.98-99.9999.99-99.99
    No. of true HIV-positive results (%)31.2189.7092.31
    No. of previously confirmed HIV results (%)27.22-35.4984.00-93.6286.93-95.67