Prevalence of Undiagnosed Acute and Chronic HIV in a Lower-Prevalence Urban Emergency Department

We estimated the seroprevalence of both acute and chronic HIV infection by using a random sample of emergency department (ED) patients from a region of the United States with low-to-moderate HIV prevalence. This cross-sectional seroprevalence study consecutively enrolled patients aged 18 to 64 years within randomly selected sampling blocks in a Midwestern urban ED in a region of lower HIV prevalence in 2008 to 2009. Participants were compensated for providing a blood sample and health information. After de-identification, we assayed samples for HIV antibody and nucleic acid. There were 926 participants who consented and enrolled. Overall, prevalence of undiagnosed HIV was 0.76% (95% confidence interval [CI] = 0.30%, 1.56%). Three participants (0.32%; 95% CI = 0.09%, 0.86%) were nucleic acid-positive but antibody-negative and 4 (0.43%; 95% CI = 0.15%, 1.02%) were antibody-positive. Even when the absolute prevalence is low, a considerable proportion of undetected HIV cases in an ED population are acute. Identification of acute HIV in ED settings should receive increased priority.