A diagnostic blind spot: acute infectious mononucleosis or acute retroviral syndrome

Reducing False-Positive Results With Fourth-Generation HIV Testing at a Veterans Affairs Medical Center

Background

In 2006, the Centers for Disease Control and Prevention issued guidelines advocating routine HIV screening for all patients. However, false-positive results are a potential patient care threat for low-risk populations even with accurate screening assays. A reduction in HIV false-positive screening results can potentially be seen by switching from the third-generation to a more sensitive and specific fourth-generation screening assay.

Methods

We studied the impact on the false-positive screening rate of a change to a fourth-generation assay at a regional US Department of Veteran Affairs Medical Center. HIV screening tests performed by the laboratory from March 1, 2016 to February 28, 2017, prior to implementation of the new assay were compared with fourth-generation HIV screening tests performed from March 1, 2017 to February 28, 2018.

Results

Of 7,516 third-generation HIV screening tests reviewed, 52 were reactive on the screening assay; 24 were true positives, 28 were false positives. The following year 7,802 fourth-generation HIV screening tests were performed and 23 were reactive on the screening assay; 16 were true positives and 7 were false positives. The positive predictive value for the third-generation test was 46% and 70% for the fourth-generation test.

Conclusions

There were fewer false-positive results with testing with the more specific fourth- vs third-generation assay (0.09% vs 0.37%, respectively), which was statistically significant (P = .002). This reduction in false-positive screening would reduce the laboratory workload and would save an estimated $3,875 yearly and reduce the adverse effects of false-positive screening results for patients.