These 10 patients had ‘false negative’ rapid HIV tests (10 chronically infected out of 976 with negative rapid tests; 1.0% false negative; 95% CI 0.6–1.9%). Of 18 patients who had discordant

rapid HIV tests (11 men and seven women) and underwent qualitative RNA screening, six (all men) were confirmed to be HIV negative by qualitative HIV RNA testing (Fig. 1; right side). Twelve patients with discordant rapid HIV tests had positive qualitative HIV RNA tests. Ten of these 12 patients were found to have chronic PF2341066 HIV infection with positive EIA and/or WB (10 chronically infected out of 18 with discordant rapid tests; 56% false negative; 95% CI 34–76%). In total, 20 of 994 patients (2.0%; 95% CI 1.3–3.1%) with negative or discordant rapid HIV test results were confirmed to have chronic HIV infection with subsequent serological testing (Fig. 1; shaded grey boxes). False negative rapid tests occurred with all three of the trained counsellors, and with all the rapid testing kit schemes employed during the study period (Table 2). The sensitivity for detecting chronic HIV infection using the rapid test kits was 98.5% (95% CI 97.8–99.1%). The negative Selleck GDC0068 predictive value of a negative or discordant rapid test, assuming 100% specificity, was 97.9% (95% CI 96.9–98.7%).

Using the rapid HIV test kit specificity published from Uganda [22], the negative predictive value dropped to 88.5% (95% CI 86.4–90.3%).

Including both acute HIV infections (n=11) and chronic HIV infections (n=20) discovered by the RNA screening programme, a total of 3.1% (31 of 994) of patients who tested HIV rapid test negative or discordant in the out-patient department of the hospital had readily detectable and confirmed HIV infection. We found that ∼3% of patients with negative or discordant Ketotifen rapid HIV tests in a medical out-patient department in South Africa had confirmed HIV infection using pooled HIV RNA serum screening. One per cent of patients who had a negative or discordant rapid HIV test had acute HIV infection. In addition, standard rapid HIV testing missed 2% of patients who had chronic HIV infection. Pooling serum for detection of acute infection in the setting of high HIV prevalence is feasible as long as polymerase chain reaction (PCR) technology is available. In settings like this out-patient department in Durban, 1% of patients seeking medical care would otherwise receive a negative rapid HIV test result at the time when they are maximally infective [9]. Diagnosis of acute HIV infection may prevent further HIV transmission by providing an opportunity for risk behaviour counselling [11].