Among those people with HIV in a recent United Kingdom study who said they believed they had an undetectable viral load, 96 percent were correct and 99 percent had a viral load below 1,000 according to laboratory testing, aidsmap reports.

Research has found that having an undetectable viral load is associated with an extremely low risk of transmitting HIV; in fact, the risk may be zero. Even viral loads above the threshold of detection, which in this study was 50 (the threshold varies by test), but below 1,000 are believed to pose a very low risk of transmission. Aware of such research findings, people with HIV may base their sexual risk taking, such as use of condoms, on their current viral load; the accuracy of their assessment of their viral load, therefore, is particularly important.

Between 2011 and 2012, researchers form the UK Antiretroviral Sexual Transmission Risk and Attitudes (ASTRA) study recruited 2,678 people receiving HIV treatment at clinics in the United Kingdom. The participants completed a questionnaire about whether they believed their viral load was undetectable (below 50) or detectable (above 50) or whether they did not know. The researchers compared their answers to medical records of their current viral load according to laboratory testing.

Sixty-three percent of the participants had been taking HIV treatment for more than five years. One in four of them said they had missed one dose of treatment during the previous two weeks, while 17 percent reported missing doses two or more days in a row for at least one stretch during the previous three months.

Eighty-seven percent of the participants had an undetectable viral load according to lab testing. Eighty percent of the overall group believed they had an undetectable viral load, while 9 percent said they had a detectable viral load and 11 percent did not know.

Among the 2,334 participants with an undetectable viral load according to lab testing, 88 percent correctly stated they had an undetectable viral load, 2 percent incorrectly believed they had a detectable viral load and 9 percent were unsure.

Among the 344 participants with a lab-verified detectable viral load, 53 percent stated correctly that they were detectable. Twenty-two percent of this overall group said they had an undetectable viral load and 25 percent did not know.

Looking at the 2,137 people who said they had an undetectable viral load, the researchers found that 96 percent of them had an accurate perception according to lab testing. Encouragingly, the vast majority of the remaining 76 people (3.6 percent) had a detectable viral load still in the realm of very low transmission risk: 48 of them (2.2 percent) had a viral load between 51 and 199; and 13 of them (0.6 percent) had a viral load between 200 and 999. Just 15 of them (0.7 percent) had a viral load above 1,000. This meant that 99.3 percent of all of those in the study who said they had an undetectable viral load indeed had a viral load low enough to keep their risk of transmission extremely low, and possibly nonexistent.

On the whole, the self-reported viral load and lab-tested viral load results matched for 84 percent of the participants.

The investigators found that certain factors were linked to an increased risk of having an inaccurate perception of viral load status, including: having insufficient money for basic needs, which increased the risk by 2.4-fold; having poor English fluency, which increased the risk by 3.5-fold; not having disclosed having HIV, which increased the risk by 1.7-fold; not being adherent to HIV treatment, which increased the risk by 2.1-fold; and having depressive symptoms, which increased the risk by 1.9-fold.

To read the aidsmap article, click here.

To read the study, click here.