Effect of Medicaid Expansions on HIV Diagnoses and Pre-Exposure Prophylaxis Use

Introduction: Increased insurance coverage and access to health care can increase identification of undiagnosed HIV infection and use of HIV prevention services such as pre-exposure prophylaxis. This study investigates whether the Medicaid expansions facilitated by the Affordable Care Act had these effects. Methods: A difference-in-differences design was used to estimate the effects of the Medicaid expansions using data on HIV diagnoses per 100,000 population, awareness of HIV status, and pre-exposure prophylaxis use. The analyses involved first calculating differences in new diagnoses and pre-exposure prophylaxis use before and after the expansions and then comparing these differences between treatment counties (i.e., all counties in states that expanded Medicaid) and control counties (i.e., all counties in states that did not expand Medicaid). Further analyses to investigate mechanisms addressed associations with HIV incidence, rates of sexually transmitted infections, and substance use. Analyses were conducted between August 2019 and July 2020. Results: Medicaid expansions were associated with an increase in HIV diagnoses of 0.508 per 100,000 population, or 13.9% (p=0.037), particularly for infections contracted via injection drug use and among low-income, rural counties with a high share of pre–Affordable Care Act uninsured rates that were most likely to be affected by the expansions. In addition, Medicaid expansions were associated with improvements in the knowledge of HIV status and pre-exposure prophylaxis use. There was no impact of the expansions on incident HIV, substance use, or sexually transmitted infection rates with the exception of gonorrhea, which decreased after the expansions. Altogether, these results suggest that the changes in new HIV diagnoses, awareness of HIV status, and pre-exposure prophylaxis were not simply because of a higher incidence or an increase in infection risk. Conclusions: Medicaid expansions were associated with increases in the percentage of people living with HIV who are aware of their status and pre-exposure prophylaxis use. Expanding public health insurance may be an avenue for curbing the HIV epidemic.