Investigation of False Positive Results with an Oral Fluid Rapid HIV-1/2 Antibody Test

Abstract

BackgroundIn March 2004, the OraQuick® rapid HIV antibody test became the first rapid HIV test approved by the US Food and Drug Administration for use on oral fluid specimens. Test results are available in 20 minutes, and the oral fluid test is non-invasive. From August 2004–June 2005, we investigated a sudden increase in false-positive results occurring in a performance study of OraQuick® oral-fluid rapid HIV tests in Minnesota.Methodology/Principal FindingsIn a field investigation, we reviewed performance study data on oral-fluid and whole-blood OraQuick® rapid HIV test device lots and expiration dates and assessed test performance and interpretation with oral-fluid and whole-blood specimens by operators who reported false-positive results. We used multivariate logistic regression to evaluate client demographic and risk characteristics associated with false-positive results. Next, we conducted an incidence study of false-positive OraQuick rapid HIV tests in nine US cities and tested both oral-fluid and finger-stick whole-blood specimens from clients; reactive tests were confirmed with Western blot. Sixteen (4.1%) false-positive oral-fluid results occurred in the performance study from April 15, 2004 through August 31, 2004 with unexpired devices from six test lots among 388 HIV-uninfected clients (specificity, 95.9%; 95% CI: 93.4–97.6). Three test operators who had reported false-positive results performed and interpreted the test according to package-insert instructions. In multivariate analysis, only older age was significantly associated with false-positive results (adjusted odds ratio = 4.5, 95% CI: 1.2–25.7). In the incidence study, all valid oral-fluid and whole-blood results from 2,268 clients were concordant and no false-positive results occurred (100% specificity).Conclusions/SignificanceThe field investigation did not identify a cause for the increase in false-positive oral-fluid results, and the incidence study detected no false-positive results. The findings suggest this was an isolated cluster; the test's overall performance was as specified by the manufacturer.

Use of IgG in Oral Fluid To Monitor Infants with Suspected Congenital Toxoplasmosis

“…Whether current infection can induce false-positive results remains to be investigated. False-positive results have already been observed in a test for HIV in oral fluids in a cluster of patients but have also remained unexplained (24). Taken together, these data demonstrate a good parallel in the evolution of IgG titers in oral fluid and sera.…”

Oral fluid-based rapid HIV testing: issues, challenges and research directions

“…These studies have evaluated various outcomes, such as diagnostic accuracy, client preference, acceptability, uptake and cost-and time-effectiveness [13][14][15][16][17]. It is now an established fact that diagnostic accuracy of oral rapid point-of-care tests is high and that their test results are consistent across developed and developing countries [7,13,18]. However, although accuracy is very high, oral fluid test results are considered preliminary.…”

“…For example, in 2005, there were reports of falsepositive results with the oral OraQuick test from selected clinics in New York city and San Francisco in the USA [18]. However, subsequent investigations by the CDC were unable to clarify whether the quality of kits or inadequate quality control was responsible for the false-positive results [7,18]. By contrast, more recently, a study from India showed 100% sensitivity and specificity of the oral fluid-based OraQuick RAPID HIV1/2 test, demonstrating excellent performance of oral fluid testing even in a rural setting in India [13].…”

Rapid Human Immunodeficiency Virus Test Quality Assurance Practices and Outcomes among Testing Sites Affiliated with 17 Public Health Departments

“…Health departments used comprehensive rapid test training programs which were not uniform across health departments, in part because state regulations for HIV testing vary. Although our survey and previous reports (5,8) suggest that CLIA-waived rapid testing is usually conducted according to manufacturers' instructions, we found that some QA practices could be improved. Despite CLIA requirements to perform testing according to manufacturers' instructions, only 65% of health departments required staff members to read the package insert (3).…”

“…Mistakes that can occur during the testing process include performing testing outside of recommended temperatures, collecting specimens incorrectly, documentation errors, improper performance of testing, and incorrect interpretation of results (7). Adherence to QA procedures and ongoing test performance monitoring should reduce the number of testing mistakes that occur and increase the accuracy of results (5,6,8,13).The Centers for Disease Control and Prevention (CDC) developed guidelines for the implementation and operation of rapid test QA programs (4). The CDC recommends that testing sites participate in external quality assessments to evaluate how well testing is being performed.…”