Thanks to improvements in the potency of antiretrovirals (ARVs), the level of adherence needed to achieve full suppression of HIV with today’s regimens may be lower than previously conceived, aidsmap reports. In other words, such medications have greater “dosing forgiveness.”

Publishing their findings in the Journal of Acquired Immune Deficiency Syndromes, Kathy Byrd, MD, MPH, of the Centers for Disease Control and Prevention (CDC), and colleagues analyzed data from the Patient-Centered HIV Care Model demonstration project, which included 765 people with HIV between 2014 and 2016.

The study provided 12 to 48 months of data on each participant, including their demographics, viral load test results and prescription fills. A key metric to evaluate adherence was the proportion of days covered (PDC), which means the proportion of a 365-day periodduring which each participant had ARVs available based on his or her prescription refill frequency.

The study authors broke down their findings according to PDC ranges: less than 50%, 50% to just under 80%, 80% to just under 85%, 85% to just under 90% and 90% or greater. They used those rates to calculate the average adherence level required to achieve a viral load below 200 in 90% of a group.

Of the 570 people eligible for this analysis, meaning they had at least one viral load test result that had a corresponding PDC value, 53% were older than 50 years old, 40% were Black, 78% were men and 85% did not have private insurance.

There were 2,427 viral load tests, of which two thirds were linked with a PDC of at least 90%. The majority of the results were under 200.

Thirty-one percent of the participants were on integrase inhibitor ARV regimens, 21% were on non-nucleoside reverse transcriptase inhibitor (NNRTI) regimens, 18% were on protease inhibitors (PI) regimens and 30% were on other types of regimens.

There were no significant differences in the likelihood of viral suppression between those with a PDC of 80% to 85% or 85% to 90%, compared with those with a PDC of 90% or greater.

Those in the “other” regimen group had a lower likelihood of viral suppression compared with those taking a PI-based regimen. There were no significant differences in the likelihood of viral suppression based on regimen type between any of the other regimen groups.

Overall, the participants needed to have a PDC of just 82% in order for 90% of them to achieve viral suppression. Based on regimen type, the comparable required PDC was 75% for integrase inhibitor regimens, 78% for NNRTI regimens, 87% for PI regimens and 99% for the “other” regimens.

“The [ARV treatment] adherence level necessary to reach HIV viral suppression may be lower than previously thought and may be regimen dependent,” the study authors concluded.

To read the aidsmap article, click here.

To read the study abstract, click here.