Oakland, CA—Medication adherence appears to be very high soon after patients are prescribed pre-exposure prophylaxis (PrEP) to protect against HIV but begins to drop, especially among groups who most need it.

That’s according to a recent report in JAMA Network Open.

The study, using information from 13,906 members of Kaiser Permanente in Northern California, referred for PrEP, therapy between 2012 and 2019 found that specific groups were more likely to stop taking PrEP. Those include young people, Black and Latino individuals, women, and people with substance-use disorders.

“The findings have important implications that suggest access to health care is a great way to get people in the door, but we need more effective strategies for making sure people who have an ongoing need for PrEP stay on the medication,” explained lead author Carlo Hojilla, RN, PhD, a research fellow with the Kaiser Permanente Northern California Division of Research. “These are groups we want to reach, and we need innovative approaches to keep them engaged in PrEP care.”

Noting that long-term follow-up is needed to evaluate gaps in PrEP care delivery and to identify those who fall out of care, the study team sought to characterize thje continuum of care, including prescription, initiation, discontinuation, and reinitiation, and evaluation of incident HIV infections.

For the study, patients were followed up from either a PrEP referral or PrEP-coded encounter until March 2019, HIV diagnosis, discontinuation of health plan membership, or death. Analysis occurred from December 2019 to January 2021.

Participants had a median age of 33 years; 95.1% were men and 48.7% were white. Over total follow-up of 26,210 person-years, 88.1% (95% CI, 86.1%-89.9%) were prescribed PrEP and of those, 98.2% (95% CI, 97.2%-98.8%) initiated PrEP.

Results indicate that, after PrEP initiation, 52.2% (95% CI, 48.9%-55.7%) discontinued PrEP at least once during the study period, and 60.2% (95% CI, 52.2%-68.3%) of these individuals subsequently reinitiated.

“Compared with individuals aged 18 to 25 years, older individuals were more likely to receive a PrEP prescription (e.g., age >45 years: hazard ratio [HR], 1.21; 95% CI, 1.14-1.29) and initiate PrEP (e.g., age >45 years: HR, 1.09; 95% CI, 1.02-1.16) and less likely to discontinue (e.g., age >45 years: HR, 0.46; 95% CI, 0.42-0.52),” the authors advise.

In addition, they note, African American and Latinx individuals were less likely to receive a PrEP prescription (African American: HR, 0.74 [95% CI, 0.69-0.81]; Latinx: HR, 0.88 [95% CI, 0.84-0.93]) and initiate PrEP (African American: HR, 0.87 [95% CI, 0.80-0.95]; Latinx: HR, 0.90 [95% CI, 0.86-0.95]) compared with White patients. They also were more likely to discontinue (African American: HR, 1.36 [95% CI, 1.17-1.57]; Latinx: 1.33 [95% CI, 1.22-1.46]).

Others groups--women, individuals with lower neighborhood-level socioeconomic status (SES), and substance use disorder (SUD) patients – also were less likely to be prescribed (women: HR, 0.56 [95% CI, 0.50-0.62]; lowest SES: HR, 0.72 [95% CI, 0.68-0.76]; SUD: HR, 0.88 [95% CI, 0.82-0.94]) and initiate PrEP (women: HR, 0.71 [95% CI, 0.64-0.80]; lower SES: HR, 0.93 [95% CI, 0.87-.0.99]; SUD: HR, 0.88 [95% CI, 0.81-0.95]) and more likely to discontinue (women: HR, 1.99 [95% CI, 1.67-2.38]); lower SES: HR, 1.40 [95% CI, 1.26-1.57]; SUD: HR, 1.23 [95% CI, 1.09-1.39]).

The study found that HIV incidence was highest among individuals who discontinued PrEP and did not reinitiate PrEP (1.28; 95% CI, 0.93-1.76 infections per 100 person-years).

“These findings suggest that gaps in the PrEP care continuum were concentrated in populations disproportionately impacted by HIV, including African American individuals, Latinx individuals, young adults (aged 18-25 years), and individuals with SUD,” the researchers conclude. “Comprehensive strategies to improve PrEP continuum outcomes are needed to maximize PrEP impact and equity.”

As to why PrEP users discontinued prescriptions, the authors note that prior studies have also documented medical mistrust, stigma, homophobia, and transphobia as barriers to uptake and persistence in some communities.

“We know cost can be a big concern for some people, and this study included a time period before PrEP-related services were provided at no cost as a result of changes in recommendations by the U.S. Preventive Services Task Force,” Dr. Hojilla said.

The study was also carried out before the introduction of a new option for dosing known as 2-1-1, or on-demand, which allows the user to take PrEP only around the time of a potential exposure to HIV, with a similar level of effectiveness as daily dosing.

Senior author Jonathan Volk, MD, an infectious-disease specialist with The Permanente Medical Group, suggests the possibility that some of the discontinuation documented in the study was from patients who opted to not take the drug daily because they had only occasional risk exposure, even prior to 2-1-1 dosing being formally recommended.

No new HIV infections were identified among those who remained on PrEP therapy, Dr. Volk notes, adding, “This shows how incredibly well PrEP works when taken. “But there are important opportunities for us to maximize the population level impact of this vital therapy. To do this, we need to avoid attrition along the care continuum, especially by assisting patients to stay on PrEP throughout periods of risk for HIV acquisition.”

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.