Using Structural Equation Modeling to Examine Barriers and Facilitators of HIV Pre-Exposure Prophylaxis Willingness and Length of Use in Men Who Have Sex with Men Who Use Substances in Eight Southern US Cities.

Men who have sex with men who use substances (SU-MSM) can benefit from pre-exposure prophylaxis (PrEP) for HIV prevention, especially in Southern US cities where HIV incidence is high; however, uptake remains low. Identifying barriers and facilitators is crucial for developing and implementing strategies to enhance uptake. Few studies of PrEP barriers and facilitators have focused on Southern SU-MSM, and most existing studies have not robustly measured such barriers and facilitators. In this study, 225 SU-MSM were recruited from community STI clinics, syringe services programs, or substance use treatment programs in eight Southern cities. Using structural equation modeling, we examined latent variable constructs of barriers and facilitators (i.e., affordability, burden, risk compensation, side effects, and stigma) and their associations with both willingness to take PrEP and length of PrEP use. Greater concern over affordability was robustly associated with more willingness to take PrEP under a variety of conditions. Risk compensation was associated with greater length of PrEP use, suggesting a major motivator to remain on PrEP was the perceived freedom to forego condoms during sex. Findings advance research on measurement of barriers and facilitators of PrEP willingness and uptake and highlight the importance of addressing affordability in PrEP implementation.