Pools were initially screened qualitatively with Roche COBAS AmpliScreen HIV-1 Test version 1.5 (Roche Molecular Systems, Branchburg, NJ, USA). Quantitative RNA testing on individual positive specimens was then performed using Roche COBAS Amplicor

HIV-1 version 1.5. All patients with a positive individual quantitative HIV RNA screen underwent antibody testing with HIV EIA [Vironostika HIV-1 Microelisa System (Biomérieux, Durham, NC, USA) or HIV-1 rLAV EIA (Bio-Rad, Richmond, WA, USA) and HIV WB (Bio-Rad). Patients were defined as having acute HIV infection if they had an HIV RNA level >10 000 HIV-1 RNA copies/mL with either negative HIV antibody testing or HIV GDC-0068 mouse EIA positivity with a negative or indeterminate WB [16]. Patients were defined as having chronic HIV infection if they had both positive EIA and WB in the presence of elevated HIV RNA (>5000 copies/mL) [21]; these patients were considered to have ‘false negative’ rapid test results. The highest HIV RNA among chronically AP24534 infected patients was reported as >750 000 copies/mL (the upper limit of the assay); this was considered 750 000 copies/mL for the purpose of the analysis. One patient

had a positive qualitative RNA screen but had neither WB nor HIV RNA available and was excluded from further analysis. Within the first month of the study, there were several patients identified via RNA testing with chronic infection and false negative rapid tests results. After the first three false negative rapid test results, the HIV testing protocol in the out-patient department was evaluated. Because the issue initially appeared to involve false Adenosine negatives from a single lot of confirmatory test kits (i.e. the second

rapid test performed in series to confirm an initial positive test), that test lot was promptly discarded (SmartCheck). The local Department of Health was notified of the findings and a new confirmatory rapid test kit was adopted (SD Bioline). The counsellors performing the rapid HIV tests were retrained in testing techniques by representatives from one of the HIV test kit manufacturers. Counsellors’ offices were already air-conditioned in an effort to control temperature and humidity for optimal test integrity. During the last 3 months of the study period, when false negatives continued to occur, the hospital adopted a parallel rapid testing algorithm as described above. The main study outcome was the proportion of subjects with acute HIV infection among patients with negative or discordant rapid tests. The second study outcome was the proportion of patients with chronic HIV infection among patients with negative or discordant rapid tests (false negative rapid test). Ninety-five per cent confidence intervals (CIs) around prevalence estimates of acute and chronic HIV infection were calculated using the binomial distribution. We evaluated the performance of rapid HIV tests compared with that of serological tests performed on venipuncture samples.