Interpretation of indeterminate HIV serology results in an incarcerated population

HIV serologically indeterminate individuals: Future HIV status and risk factors

BACKGROUND

Indeterminate HIV test results are common, but little is known about the evolution of indeterminate serology and its sociodemographic and behavioral correlates. We assessed future HIV serological outcomes for individuals with indeterminate results and associated factors in Rakai, Uganda.

METHODS

115,944 serological results, defined by two enzyme immunoassay (EIAs), among 39,440 individuals aged 15-49 years in the Rakai Community Cohort Study were assessed. Indeterminate results were defined as contradictory EIAs. Modified Poisson regression models with generalized estimating equations were used to assess prevalence ratios (PRs) of subsequent HIV serological outcomes and factors associated with HIV indeterminate results.

RESULTS

The prevalence of HIV serologically indeterminate results was 4.9%. Indeterminate results were less likely among women than men (adjPR 0.76, 95% CI 0.71,0.81), in unmarried participants than married participants (adjPR 0.92, 95% CI 0.85,99), and in individuals with primary (adjPR 0.90, 95% CI 0.80,1.02), secondary (adjPR 0.83, 95% CI 0.73,0.96) and post-secondary (adjPR 0.75, 95% CI 0.60,0.94) education, relative to no education. The proportions of persons with indeterminate results progressing to HIV positive, negative or indeterminate results in subsequent visits was 5%, 71% and 24%, respectively.

CONCLUSION

HIV serologically indeterminate results were associated with gender and marital status. HIV surveillance programs should develop a protocol for reporting individuals with mixed or persistently indeterminate HIV results on multiple follow-up visits. Most indeterminate results became HIV-negative over time, but follow-up is still needed to detect positive serologies.

False-positive human immunodeficiency virus enzyme immunoassay results in pregnant women

OBJECTIVE

Examine whether false-positive HIV enzyme immunoassay (EIA) test results occur more frequently among pregnant women than among women who are not pregnant and men (others).

DESIGN

To obtain a large number of pregnant women and others tested for HIV, we identified specimens tested at a national laboratory using Genetic Systems HIV-1/HIV-2 Plus O EIA from July 2007 to June 2008.

METHODS

Specimens with EIA repeatedly reactive and Western blot-negative or indeterminate results were considered EIA false-positive. We compared the false-positive rate among uninfected pregnant women and others, adjusting for HIV prevalence. Among all reactive EIAs, we evaluated the proportion of false-positives, positive predictive value (PPV), and Western blot bands among indeterminates, by pregnancy status.

RESULTS

HIV prevalence was 0.06% among 921,438 pregnant women and 1.34% among 1,103,961 others. The false-positive rate was lower for pregnant women than others (0.14% vs. 0.21%, odds ratio 0.65 [95% confidence interval 0.61, 0.70]). Pregnant women with reactive EIAs were more likely than others (p<0.01) to have Western blot-negative (52.9% vs. 9.8%) and indeterminate results (17.0% vs. 3.7%) and lower PPV (30% vs. 87%). The p24 band was detected more often among pregnant women (p<0.01).

CONCLUSIONS

False-positive HIV EIA results were rare and occurred less frequently among pregnant women than others. Pregnant women with reactive EIAs were more likely to have negative and indeterminate Western blot results due to lower HIV prevalence and higher p24 reactivity, respectively. Indeterminate results may complicate clinical management during pregnancy. Alternative methods are needed to rule out infection in persons with reactive EIAs from low prevalence populations.

Communicating indeterminate HIV Western blot test results to clients: an observational study of three community testing sites

This study examined HIV test counselors' beliefs and practices regarding communicating indeterminate HIV test results to clients. There are many reasons for an indeterminate HIV antibody/ Western blot assay including early HIV infection, infection with other contagious diseases, autoimmune diseases, and second or subsequent pregnancies in women. Field observations of three community HIV testing sites and semistructured interviews with 16 HIV test counselors were conducted from August 2002 through June 2003. Counselors defined an indeterminate test result in different ways. They also presented several different theories of causation, yet failed to mention two potential causes of an indeterminate result, association with large animals and infection with other (non-HIV-1) HIV strains. Counselors' understanding of the meaning of an indeterminate HIV test result varied a great deal. Some counselors believed that an indeterminate result truly was ambiguous while others believed it was indicative of being either HIV-positive or HIV-negative. Counselors' primary advice to clients who received an indeterminate result was to retest immediately without a waiting period. Counselors reported that communicating indeterminate test results to clients was a challenging task because clients who received such a result were confused, angry, and/or mistrustful. Results highlight the need for further research to provide reliable estimates of the extensiveness of indeterminate HIV test results and to further assess the nature of counselor and client responses to indeterminate test results.

HIV Infection: Point-of-Care Testing

OBJECTIVE

To review the data regarding point-of-care testing for the diagnosis of HIV infection in the US.

DATA SOURCES

English-language literature was identified via MEDLINE (1980—August 2003) using key words such as rapid HIV tests and HIV antibody testing. Textbooks and other pertinent resources were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

All articles identified through the data sources above were evaluated and reviewed if pertinent to the objective.

DATA SYNTHESIS

The Centers for Disease Control and Prevention (CDC) has announced an effort to expand currently recommended strategies to prevent new infections with HIV. The cornerstone of this initiative is the availability of the new rapid test for antibodies to HIV (OraQuick Rapid HIV-1 Antibody Test, OraSure Technologies, Bethlehem, PA). The effectiveness, sensitivity, and specificity of this test have been evaluated in a number of cross-sectional studies using previously or simultaneously performed HIV enzyme immunoassays with Western blot confirmation as a reference standard. Although there are several limitations to consider, results of these studies suggest that this test has comparable ability to detect HIV antibodies to other commercially available tests.

CONCLUSIONS

The OraQuick test is simple enough to be performed in many settings including those that facilitate achievement of the goals outlined by the CDC. Availability of this test should have a dramatic impact on HIV detection and prevention strategies.

Laboratory testing for infection with the human immunodeficiency virus: established and novel approaches

The enzyme-linked immunosorbent assay (ELISA) and the Western blot are the primary tests for the diagnosis and confirmation of human immunodeficiency virus (HIV) infection. The ELISA, an inexpensive screening test for antibodies to HIV-1, is both sensitive and specific. The HIV-1 Western blot is a reliable confirmatory test following a repeatedly reactive ELISA. False-positive HIV-1 results with this sequence of tests are extremely rare but can occur, and test results that are inconsistent with clinical or other laboratory information should be questioned, repeated, or supplemented. The US Food and Drug Administration has also approved rapid and more accessible testing methods. Oral mucosal transudate and urine testing are noninvasive testing methods; rapid and home sample collection kits offer easier access to testing.