HIV pre-exposure prophylaxis prescription initiation and maintenance among homeless-experienced people who use drugs.

Background: HIV pre-exposure prophylaxis (PrEP) remains particularly underutilized among homeless-experienced people who use drugs (PWUD).

Setting: Boston Health Care for the Homeless Program, a Federally Qualified Health Center serving homeless-experienced individuals in Boston, Massachusetts.

Methods: To identify determinants of PrEP prescription initiation and continuation, we analyzed electronic medical records and pharmacy data between April 2018-March 2022. Participants were HIV-negative and reported sexual, drug, or community-related HIV exposures. Adjusted multinomial logistic regression explored associations between sociodemographics, social vulnerabilities, behavioral factors (e.g., injection drug use), and mental health and substance use disorder diagnoses with filling of one and more than one PrEP prescription.

Results: Among 509 participants, mean age was 38 years, 28% were women, 19% were Black, and 24% were Hispanic/Latino. At program enrollment, most were experiencing homelessness (92%), injecting drugs (78%), and living with a mental health disorder (71%). In multivariable-adjusted models, injection drug use was positively associated with filling one and more than one PrEP prescription (adjusted odds ratio [AOR]: 2.88, 95% confidence interval [CI]: 1.33-6.26; and AOR: 3.60, 95% CI: 2.02-6.42, respectively). Participants with opioid use disorder and generalized anxiety disorder were more likely to fill one and more than one prescription, while those with bipolar disorder were less likely to fill one prescription. No sociodemographic characteristics, sexual behaviors or other mental health or substance use disorders were associated with study outcomes.

Conclusion: A low-threshold, harm reduction-oriented PrEP program supported prescription initiation and continuation for homeless-experienced PWUD. Implementation research is needed to facilitate scale-up of this approach.