About 1.1 million Americans were living with HIV in 2019 with the total lifetime cost to treat a single person with an HIV infection estimated to be around $501,000. Huge disparities in new HIV incidences exist between different geographic and demographic groups, with Southern US accounting for about 52% and men accounting for 79.2% of all new cases in the country. In February 2019, "Ending the HIV Epidemic: A Plan for the United States" was proposed, with pre-exposure prophylaxis (PrEP) being a major component of the prevention strategy. PrEP, a pill taken daily by mouth, contains antiretroviral drugs and is highly effective in preventing the acquisition of HIV. Despite the fact that PrEP coverage in the US improved from 9% in 2016 to 18% in 2018, huge disparities in PrEP prescriptions exist in different geographic, racial/ethnic, and age groups. Existing metrics to measure PrEP coverage like the PrEP-to-need ratio, defined as the ratio of number of patients with at least one day of PrEP prescription in a year to new HIV cases overestimates PrEP coverage. Moreover, previous studies conducted at the national and state levels often fail to capture disparities in PrEP use within the county and cannot be used by county public health officials to conduct targeted interventions.In this dissertation I develop an evaluation framework for HIV prevention using novel metric bounds encompassing PrEP patient, and pills count for measuring PrEP usage at subcounty level, as well as an evaluation framework to quantify the effects of Public Health Interventions (PHIs) on PrEP usage. Pharmacy claims data for PrEP along with HIV incidences and census data for Mecklenburg County from 2013–2019 will be used in the analysis. The following specific aims are followed to accomplish this objective: Aim 1: Aggregate ZIP codes to avoid potential patient re-identification, Aim 2: Establish a novel bounds for the likely PrEP-to-need ratio in different geographic and demographic groups, and Aim 3: Evaluate the influence of G2Z-MC on monthly PrEP users.The 29 ZIP codes in Mecklenburg County were aggregated into 13 geographically adjacent ZIP code groups to avoid the risk of potential patient re-identification. From 2013 to 2019, there were 2,045 PrEP patients and 466,525 PrEP pills dispensed in Mecklenburg county. The population-adjusted PrEP patients per 100,000 increased from 5.64 to 106.39 and pills dispensed increased from 3,609 to 187,050. The overall [dose adjusted PrEP-to-need ratio (daPnR), PrEP-to-need ratio (PnR)] range increased from [0.0578, 0.3275] to [2.1176, 4.9628]. The [daPnR, PnR] ratio range increased from [0.053, 0.5] to [0.717, 2.09] for females and from [0.059, 0.285] to [2.429, 5.601] for male. Patients aged ≥ 45 years had a notable increase in [daPnR, PnR] ratio range from [0.079, 0.458] to [3.56, 6.649]. The ZIP code group containing main campuses of the two largest Mecklenburg County hospitals and a specialty pharmacy had a notable increase in [daPnR, PnR] ratio range from [0.275, 2.5] to [10.236, 22.67]. The G2Z-MC intervention had a significant gradual effect of about nine PrEP patients every month.PnR and daPnR ratios increased from 2013 to 2019. However, female patients, aged ≤ 24 years, or belonging to certain ZIP code groups are underserved. Our results indicate the need for focused efforts to make PrEP more accessible for underserved populations. The results of this dissertation quantified and identified opportunities for improvement in PrEP use within Mecklenburg County in different geographic and demographic groups. This study also establishes a framework to evaluate the effects of Public Health Interventions (PHIs) on PrEP usage in Mecklenburg County. This work can be extended to other counties and will also provide a foundation to conduct similar studies for other emerging infectious diseases.
