Variables that predict whether veterans will adhere well to the daily regimen of Truvada (tenofovir disoproxil fumarate/emtricitabine) as pre-exposure prophylaxis (PrEP) include being older and white, the National AIDS Treatment Advocacy Project (NATAP) reports.

This conclusion from a recent analysis conducted by researchers at the Veterans Health Administration (VHA) is in keeping with a slew of findings from other investigations: that PrEP’s benefits tend to go toward a limited demographic of white men who have sex with men (MSM) older than 25. Meanwhile, the demographic at highest risk for HIV, Black MSM, especially those younger than 25, tend to get left out of this form of medication-based prevention of the virus.

Presenting their findings at the IDWeek 2017 conference in San Diego, VHA investigators analyzed medical records of veterans to assemble a cohort of 1,086 individuals who received PrEP between July 2012 and July 2016. They assessed adherence through pharmacy refill data by determining the proportion of days covered by Truvada during the first year after an individual first received PrEP; high adherence meant more than 80 percent of days were covered.

If an individual went 120 days without refilling Truvada, they were considered to have stopped taking PrEP.

Ninety-six percent of the cohort was male, 67 percent was white and 22 percent was Black. They had an average age of 41; 27 percent were 50 or older. Nine percent had diabetes. Based on the ZIP codes in which vets lived, the investigators determined that 48 percent resided in a low-poverty area, 34 percent in a moderate-poverty area, 10.5 percent in a high-poverty area and 5 percent in an extreme-poverty area. Ninety-six percent lived in an urban area.

Forty-four percent of the vets stopped taking PrEP within a year.

The average adherence rate was 74 percent. For the different age brackets, the adherence rate was: younger than 35, 66 percent; 35 to 49, 74 percent; 50 to 64, 79 percent; and 65 to 79, 73 percent. The rate for males was 74 percent and for females was 27 percent. The rate for whites was 74 percent, for those of “other” race was 74 percent and for Blacks was 58 percent. The respective rate for those who did and did not abuse substances was 66 percent and 74 percent.  And the respective rate for those who did and did not have diabetes was 89 percent and 74 percent.

After adjusting the data for various factors, the researchers found that, compared with being younger than 35, being 35 to 49 years old was associated with a 1.36-fold increase likelihood of adhering at a rate of 80 percent or higher, and being 50 to 64 years old was associated with a 2-fold increase likelihood of good adherence. Compared with females, males were 3.39-fold more likely to adhere well. Compared with Blacks, whites and those of “other” race were a respective 2.02-fold and 2.05-fold more likely to adhere well. And compared with those without diabetes, those with the condition were 2.02-fold more likely to adhere well.