Expanding Pharmacists' Prescribing Authority and Medication Uptake: Evidence From Pre-Exposure Prophylaxis.

Introduction: Considering the crisis in access to care in the U.S., pharmacies are expected to significantly expand access to a variety of preventive care, including HIV care. As of August 2024, 10 states allow pharmacists to initiate pre-exposure prophylaxis, a medicine taken to prevent HIV, independently. This study analyzed how the expansion of pharmacists' authority to independently initiate pre-exposure prophylaxis affected pre-exposure prophylaxis prescription rates per 100,000 county residents. Methods: Hand-collected data on pharmacists' prescribing authority from 2015 to 2023 were linked to county-level pre-exposure prophylaxis prescription rates. Using these data, the impact of the laws was estimated through a difference-in-differences approach. The analysis first calculated changes in pre-exposure prophylaxis prescription rates before and after the expansions and then compared these changes between counties in states that expanded pharmacists' scope of practice (treatment group) and counties in states that did not (control group). Results: Expanding pharmacists' prescribing authority increased pre-exposure prophylaxis prescription rates by 11.6%. The largest effects were observed in states that allowed pharmacists to prescribe pre-exposure prophylaxis without any mandatory training, a requirement that may otherwise burden pharmacists. Effects were most prominent in nonrural counties and counties with high insurance coverage and lower proportions of Black and Latinx populations. Conclusions: These results suggest that expanding pharmacists' prescribing authority will not improve disparities in pre-exposure prophylaxis use if the laws fail to address structural barriers, such as staffing constraints or a lack of capacity.