A fourth-generation, antigen/antibody laboratory HIV screening test that produces rapid results was practical in the emergency department setting and successfully identified new infections in the acute stage, study findings suggest.

Although detection of HIV during the acute stage is critical in reducing transmission rates and improving long-term outcomes, previous testing modalities have had difficulty identifying HIV infection during this stage, according to background information provided in the study.

To assess the prevalence of both acute and chronic unrecognized HIV with the implementation of nontargeted, opt-out HIV screening with the fourth-generation test, Maricopa Medical Center, Kara I. Geren, MD, MPH, of the Maricopa Integrated Health System in Phoenix, Ariz, and colleagues collected data from 22,468 patients aged 18 to 64 years.

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Between July 11, 2011 and Jan. 5, 2014, researchers performed 27,952 HIV screenings. Test results were delivered by a physician with the assistance of a linkage-to-care specialist. Specimens tested with the reactive fourth-generation assay result underwent further testing for confirmation.

There were 105 preliminary positive HIV test results with the fourth-generation test (95% CI: 0.30-0.45). Of these, 27 were false-positives (95% CI: 17.9-35.3). Overall, new HIV infections were diagnosed in 78 patients, of which 18 had acute infections and 22 had a CD4 count of <200 cells/mL.

Additionally, 82% of patients with a confirmed HIV diagnosis did not have health insurance. However, 72% were introduced to HIV care within 90 days.

“One of the greatest concerns about this program was asking an already overburdened, under resourced [ED] and its staff to perform a public health function,” the researchers wrote. “The total number of new HIV infections was unexpected. Even more surprising, one fourth of patients with undiagnosed HIV had acute infections. This program may serve as a model for the success of nontargeted, opt-out public health measures in an acute care setting.”


  1. Geren KI. Ann Emerg Med. 2014; doi:10.1016/j.annemergmed.2014.05.021.