Rapid HIV tests in high-income countries miss about one in seven infections and should be used in combination with fourth-generation enzyme immunoassays (EIA) or nucleic acid amplification tests (NAAT) in clinical settings, according to a study in the journal AIDS.

“These infections are likely to be particularly transmissible due to the high HIV viral load in early infection … in high-income countries, rapid tests should be used in combination with fourth-generation EIA or NAAT, except in special circumstances,” the Australian researchers said.

They performed a systematic review and meta-analysis of 18 studies involving 110,122 HIV rapid test results. The primary outcome was the test’s sensitivity for detecting acute or established HIV infections. Sensitivity was calculated by dividing the number of confirmed positive rapid tests by the number of confirmed positive comparator tests. Specificity was calculated by dividing the number of confirmed negative rapid tests by the number of negative comparator tests.

Compared with EIA, the estimated sensitivity of rapid tests was 94.5% (95% confidence interval, 87.4-97.7). Compared with NAAT, the sensitivity of rapid tests was 93.7% (95% CI, 88.7-96.5). The sensitivity of rapid tests in high income countries was 85.7% (95% CI, 81.9-88.9), and in low income countries was 97.7% (95% CI, 95.2-98·9), compared with either EIA or NAAT (P less than .01 for difference between settings). Proportions of antibody negative acute infections were 13.6% (95% CI, 10.1-18.0) and 4.7% (95% CI, 2.8-7.7) in studies from high- and low-income countries respectively (P less than .01).

Rapid tests were less sensitive when used in clinical settings in high-income countries, regardless of whether they were compared with a NAAT or fourth-generation EIA. However, the researchers noted that the discrepancy between high- and low-income countries could be attributed to the higher proportion of acute HIV infections (antibody-negative NAAT positive) in populations tested in high-income countries, which might reflect higher background testing rates or a higher incidence of HIV in men who have sex with men.

Read the full study in AIDS ( doi: 10.1097/QAD.0000000000001134 ).

On Twitter @richpizzi


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