HIV Blood Test More Accurate Than Rapid HIV Tests (February 7, 2012)
Researchers in Canada determine that oral HIV test used for rapid STD testing
results by swabbing the gums is 97% accurate in populations considered to be low risk for HIV and 99% accurate in high risk populations. Results from the oral HIV test are possible in as little as thirty minutes.
However, these rapid tests are still considerably less accurate than a standard laboratory HIV blood test
. The benefit of the oral swab test is that it makes HIV accessible and convenient. Blood tests have been less accessible due to the stigma and the necessity of having a doctor's order.
Today private HIV blood testing is available conveniently from companies such as Health Testing Centers without needing to go to a doctor. Results are private, fast (generally within 24 to 48 hours), and accurate.
There is a worldwide focus on prevention of HIV and unfortunately testing has not been in the forefront of strategies to slow the growth of HIV. The main complaint is that HIV testing is inconvenient. Oral testing makes testing easier with nearly instantaneous results. But the results show that this rapid testing is still less accurate.
In areas where less than 1 percent of the population has HIV, the positive predictive value (PPV) was 89% for oral testing compared to 99% for blood testing. Which means that the lower the percentage of the population infected with HIV the higher the percentage of false positives. Correspondingly as the percentage of the population with HIV increases the false positive percentage decreases. Despite the increased false positives the oral HIV tests were just 2% less sensitive than blood rapid HIV tests.
A main reason for the poorer performance with oral testing is that there are lower concentrations of HIV antibodies than in blood. The results are particularly effected if testing HIV after potential recent exposure when antibodies would be especially low in oral fluid but could be accurately measure in the blood (Early HIV Detection DNA PCR Test
The canadian researchers used a head to head comparison of testing gathered from five separate studies worldwide including a systematic review and meta-analysis of results from 2000 to 2011. The focus of the studies has been on the point of care HIV test Oraquick advance rapid HIV-1/2 from OraSure Technologies Inc. Oraquick is being considered for use as an over the counter test in the US and several other countries.