Comparative field evaluation of HIV rapid diagnostic assays using serum, urine, and oral mucosal transudate specimens

Background: Comparative field utility of selected HIV-1 assays using homologous collections of serum, urine and oral mucosal transudate (OMT) was determined in adult populations from a tuberculosis hospital and STD clinic in Djibouti, East Africa.

Study design: Enzyme immunoassay with confirmatory Western blot was performed on all serum specimens for comparison with rapid, instrument-free assays (SUDS HIV-1, Murex; TestPack Abbott; and COMBAIDS HIV 1 + 2, SPAN Diagnostics) using various specimen sources. Delayed (48 h post-collection) testing was also performed on urine. Sensitivity and specificity for the rapid assays, in descending order, were as follows: serum SUDS HIV-1 assay (100%, 98.3%), serum COMBAIDS assay (98.4%, 99.6%), and OMT SUDS HIV-1 assay (98.4%, 94.5%).

Results: The OMT EIA optical density cutoff value was modified resulting in an improved specificity from 89.1 to 99.6%; however, sensitivity decreased from 100 to 98.5%. Urine EIA and rapid assays demonstrated unacceptable test performance for use as a screening test.