Diagnostic detection of human immunodeficiency virus type 1 antibodies in urine: a brazilian study

We evaluated, for the first time in Latin America, the performance of a commercial enzyme immunoassay (EIA) (Calypte Biomedical Corporation, Berkeley, Calif.) that detects human immunodeficiency virus type 1 (HIV-1)-specific antibodies in urine in comparison to standard serological assays (two commercial EIAs and a commercial Western blot [WB] assay). Paired serum and urine specimens were collected from two different groups of Brazilian patients: 225 drug users with unknown HIV status who attended drug treatment centers in Rio de Janeiro, Brazil, and 135 subjects with known HIV status. Patients showing positive results in the serum EIAs and/or in the urine EIA were serologically confirmed by WB assay. For 135 individuals with known HIV status, the urine EIA showed 100% sensitivity (74 positive samples) and 95.1% specificity (58 of 61 negative specimens). For 225 drug users, the test showed 100% sensitivity (2 positive samples) and 98.7% specificity (220 of 223 negative samples) compared to WB-confirmed serological EIA results. Thus, in a total of 360 samples, the urine EIA correctly identified all 76 HIV-positive samples and 278 of 284 negative samples (100% sensitivity and 97.9% specificity). Detailed analysis of the urine EIA results indicates that an increase of the recommended cutoff value might raise the specificity of the assay without affecting its sensitivity. Our results suggest that the HIV-1 urine EIA is a good screening test suitable for developing countries like Brazil. However, as for all other HIV screening tests on the market, it is not specific enough to be used as a one-step test and therefore requires confirmation.