HIV testing: 2014 U.S. recommendations

Incidence of false positive enzyme-linked immunosorbent assay (ELISA)/enzyme immunoassay (EIA) and indeterminate western blots are expected to rise as the United States Preventive Services Task Force (USPSTF) expands its human immunodeficiency virus HIV testing recommendations to include low-risk populations. This paper explores current HIV testing recommendations, HIV testing options, causes of false positive or indeterminate results, and how clinicians should proceed when confronted with potential false positive or indeterminate results. We report two cases in which positive ELISA/EIA and indeterminate western blots required further evaluation and prove to be false positives. The USPSTF recommends aggressive HIV testing to include screening for all persons 15 to 65 years of age, and younger or older persons who are at increased risk. They also recommend screening all pregnant women, including those who are untested, who present in labor. Indeterminate western blot tests should be followed up with nucleic acid testing (NAT) or polymerase chain reaction (PCR) tests, and repeated ELISA/EIA and western blot assays at three and six months. Fourth generation tests offer an alternative and utilize HIV-1/HIV-2 antibody differentiation immunoassays, in place of western blot assays.