Applying Behavioral Economics to HIV Prevention: Development of a Novel PrEP Demand Task.

Promoting pre-exposure prophylaxis (PrEP) initiation to prevent new HIV infections among vulnerable populations continues to present significant challenges. Behavioral economics may provide a useful framework to help elucidate decision-making processes influencing valuation and use of PrEP. We developed two novel behavioral economic tasks assessing demand for PrEP pills and PrEP injection. Participants consisted of Black and Hispanic gay and bisexual men (GBM; N = 144), 18 to 34 years old, and recruited from Texas. Participants completed an online battery including PrEP demand tasks and questions related to PrEP use and intentions. Probability of purchasing PrEP treatment decreased with increasing PrEP price on both tasks and were well described by the exponentiated demand model. Five group comparisons were conducted based on reported PrEP use and intentions. Bayesian generalized linear models were used to compare those responding "Yes" vs. all others (i.e., "No", "Don't know", "Prefer not to say"), revealing generally greater PrEP pill demand among current pill users as well as generally greater PrEP injection demand among those having discussed injectable PrEP with their care-provider, planning on discussing injectable PrEP with their care-provider, and planning on taking injectable PREP (all posterior probabilities ≥ 75%) but not for those having simply heard of injectable PrEP. Findings provide initial support as to the utility and construct validity of our PrEP demand tasks, providing an initial foundation for identifying those requiring additional intervention to improve valuation and use of PrEP.