Evaluating Adherence of PrEP Therapies

Investigators wanted to study usage of F/TAF vs F/TDF in clinical practice and HIV seroconversion.

While the PrEP market is emerging as different medications and treatment options are being studied, there are 2 therapies that are Food and Drug Administration (FDA) approved currently: emtricitabine and tenofovir alafenamide (F/TAF), and emtricitabine and tenofovir disoproxil fumarate (F/TDF). Each of these medications are indicated for a once-daily oral regimen.

Investigators at Howard Brown Health in Chicago wanted to study real-world use patterns and HIV seroconversion for F/TAF and F/TDF.

Laura Rusie, ScM Director of Data, Evaluation, and Epidemiology, Howard Brown Health led the study and presented the oral abstract, Comparing Adherence to HIV PrEP Among New, Male PrEP Users Initiating F/TAF vs. F/TDF, at the 11th International AIDS Society Conference on HIV Science.

“Because of the fairly recent approval of F/TAF, there is a need for real-world contemporaneous data comparing outcomes among users using these two different regimens,” Rusie said in her presentation. “This work aims to be among the first to use real-world claims data to analyze two outcomes: adherence and HIV seroconversions for each regimen.”

They study had a total of 1113 F/TAF users and 1961 F/TDF users who met the criteria. The investigators performed a retrospective analysis of data from medical and pharmacy claims. The study looking at adult males with their first PrEP prescriptions written between October 2019 through January 2020.

According to the findings—using multivariate analysis—the investigators found that at 180 days, F/TAF users had 1.67 higher odds of adherence as compared to F/TDF users. They also noted that adherence odds increased with older populations and those with private insurance.

When looking at seroconversion, rates were not statistically different, but there was a numerical difference. “F/TAF showed a numerically lower incidence of seroconversion at all time points compared to F/TDF,” Rusie explained in her presentation. The differences in seroconversion demonstrated rates of 1.24/100 person-years for F/TAF users, and 1.80/100person-years in F/TDF users.

Contagion spoke with Rusie about her study, insights on upstream barriers to PrEP initiation, and what motivates people to stay engaged in their therapy.