Study: Older, Urban Men Most Likely to Achieve Medication Persistence with PrEP

A study evaluating patients’ persistence with HIV pre-exposure prophylaxis (PrEP) found that women and young people used the therapy for shorter amounts of time than men and older adults.

Overall, more than half of commercially insured individuals who initiated PrEP persisted with it for the 12-month duration of the cohort study.

Results of the study were presented at the Conference on Retroviruses and Opportunistic Infections (CROI), this month in Seattle, Washington, by Dr. Ya-Lin A. Huang a health scientist at the CDC in Atlanta, Georgia.

The study’s objectives were to estimate PrEP persistence among 2 cohorts of PrEP users and to assess associations between characteristics of these patients and their persistence, she said.

“In the United States, less than 10% of persons who can benefit from PrEP have initiated it,” Huang said.

“PrEP can reduce HIV incidence and help end the US HIV epidemic," she said. "However, it requires persistent use during periods of risk to be effective.”

Medication persistence differs from medication adherence, Huang said.

Medication adherence refers to the degree in which an individual takes a medication as it is recommended, in terms of dosage, frequency, and timing. Medication persistence is the length of use from initiation to discontinuation.

Using data from the IBM MarketScan Research Databases, investigators created a cohort of PrEP users aged 18 to 64 years, who initiated the therapy between January 1, 2012, and December 31, 2016. They restricted analysis to people continuously enrolled in their health plans for at least 6 months prior to and 6 months after their initial PrEP prescription. Each participant's medication fill persistence, defined as time from the initial PrEP prescription fill until there was a gap in prescription fills >30 days, was evaluated.

Throughout the 4-year study period, patients were considered nonpersistent if they did not refill within 30 days after exhausting PrEP medications from previous fills.

Investigators used Kaplan-Meier time-to-event methods to estimate the proportion of PrEP users who persisted with PrEP at 6 and 12 months after initiation and censored patients that disenrolled from insurance or were diagnosed with HIV prior to nonpersistence. The study also relied on Cox proportional hazards models for nonpersistence adjusting for age, region, sex, and urbanicity.

In a cohort of 7250 commercially insured PrEP users, 98.2% were male. Sixty-one percent were aged 25 to 44 years, and 10.6% were aged 18 to 24 years. The majority of participants (97%) resided in urban areas.

During the study period, after initiation 74.8% of PrEP users persisted for 6 months and 55.7% for 12 months. The median persistence was 14.5 months (95% CI=13.9-15.0) but was significantly shorter for female PrEP users (6.9 months; 95% CI=4.7-11.6) and for users aged 18 to 24 years (8.6 months; 95% CI=7.4- 9.3).

After adjusting for other factors, investigators found that PrEP users who were female, resided in rural areas, and young were less likely to be persistent users. The Kaplan-Meier curves of PrEP persistence stratified by age group demonstrated that PrEP persistence increased with age. Just 36.6% of the users aged 18 to 24 years persisted for 12 months compared with 65.3% aged 55 to 64 years.

The second cohort included 349 PrEP users with Medicaid insurance. These participants were 78% men, 67% aged 25 to 44 years, and 43% white.

In her presentation at CROI, Huang said that the study data show a median persistence of 14.5 months for the commercially insured study participants and 7.6 months for those with Medicaid insurance.

After 12 months of starting PrEP, 56% of commercially insured and 34% of those with Medicaid insurance continued to exercise medication persistence.

“We found that men persisted longer than women,” Huang said. “Persistence increased with age, and the youngest age group persisted for the least time.”

These trends were found in both cohort studies. For example, commercially insured PrEP users maintained medication persistence for 20.5 months in the 45 to 54 years age group but just 8.6 months for those aged 18 to 24. And for individuals insured by Medicaid, women maintained medication persistence for 5.8 months compared with 8.4 months for men.

“More than half of commercially insured persons who initiated PrEP persisted for at least 12 months, compared with a third of Medicaid users,” Huang said. “Our studies found that female sex, younger age, rural location, black race/ethnicity, and Medicaid insurance were associated with shorter periods of PrEP use.”

A better understanding of patient factors for nonpersistence is needed to support PrEP use for those people who might benefit from this therapy during periods of risk, according to the investigators.

Reference

Huang YL. Persistence with HIV Pre-exposure prophylaxis in the United States, 2012-2016. Presented at: Conference on Retroviruses and Opportunistic Infections (CROI); Seattle, WA; March 4-7, 2019.