HIV that is resistant to an extensive portfolio of antiretrovirals (ARVs) and drug classes has become increasingly rare among people living with the virus in the United States over the past 15 years, aidsmap reports.

Presenting their findings at the 10th International AIDS Society Conference on HIV Science (IAS 2019) in Mexico City, researchers analyzed data covering 2000 to 2017 regarding roughly 27,000 people receiving care for the virus at seven sites across the United States that were enrolled in the Centers for AIDS Research Network of Integrated Clinical Systems.

Eighty-one percent of the cohort members were male, 43% were white and 41% were Black. Fifty-three percent were men who had likely contracted HIV through sex with another male. The median age was 46 years old.

The study defined individuals who had multidrug resistance as those who had taken ARVs and who had a maximum of two drug classes to which their drug-resistant virus was still susceptible, including a maximum of two effective drugs in each class.

In the early study period, about 5% of the cohort members had multidrug-resistant virus. This figure peaked at 8% in 2004, then declined nearly to 2% in 2007 and stabilized at 1% by 2012.

Compared with those who started medical care for the virus between 2006 and 2008, those who entered care between 2009 and 2011 were 80% less likely to require multiple ARV regimens, and those who entered care between 2012 and 2014 were 76% less likely to require multiple ARV regimens.

Among those with multidrug-resistant virus, the median lowest-ever CD4 count was 71, compared with 240 among those without multidrug-resistant virus. The median initial viral load in these two groups was a respective 200,000 and 50,000.

A lower lowest-ever CD4 count and a higher initial viral load were each associated with a greater likelihood of developing multidrug-resistant HIV. There was no such association between changing treatment as a result of treatment failure or the number of ARVs ever taken and the chance of developing multidrug-resistant virus.

The researchers concluded that the recent introduction of new, highly potent ARVs to which HIV is less likely to develop resistance had driven the declining rate of multidrug-resistant virus.

To read the aidsmap article, click here.

To read the conference abstract, click here.