SAIA-PrEP: a systems analysis and improvement approach to optimize PrEP implementation in syringe service programs - ABSTRACT For the first time in decades, HIV incidence is increasing among people who inject drugs (PWID). Pre- exposure prophylaxis (PrEP) is a safe, effective, evidence-based HIV prevention strategy recommended for at- risk PWID. However, despite the acceptability of PrEP among PWID, access remains low, and uptake has lagged far behind that observed in other vulnerable populations. Our preliminary research demonstrates that syringe service programs (SSPs) are uniquely poised to improve PrEP access, and many already provide some services along the PrEP delivery cascade, including PrEP education, HIV testing, and linkage to onsite and external medical services. Despite being ideal venues for improving PrEP access among PWID, our data demonstrate that these agencies need additional support to optimally implement the SSP-based PrEP delivery cascade. This novel randomized controlled trial (RCT) uses an interrupted time series design to test whether an evidence-based, organization-level intervention, the Systems Analysis and Improvement Approach (SAIA), can improve the delivery of PrEP services among 32 SSPs located in Ending the HIV Epidemic priority jurisdictions. After a 3-month run-in period, SSPs will be randomized to receive SAIA (n=16) versus treatment as usual (n=16). SAIA will be delivered by trained specialists through five cyclical steps over 12 months: (1) analyze SSPs’ PrEP delivery cascade to identify priority areas for system improvements, (2) map processes and build consensus around programmatic modifications to address priority areas, (3) implement programmatic modifications, (4) assess effects of programmatic modifications on delivery of cascade services, and (5) repeat steps 1-4 as needed. SSPs will use an electronic data collection system to report on outcomes including numbers of SSP clients receiving (1) PrEP education, (2) HIV testing, (3) PrEP linkage, and (4) PrEP initiation verification. Data will be collected during the 3-month run-in period prior to randomization, and then for an additional 24 months, allowing us to identify initial impacts of SAIA after 12 months (Aim 1) and sustained impacts at 24 months (Aim 2). Outcomes will be disaggregated by sex and race/ethnicity to allow for process monitoring of programmatic changes to address equity in service delivery. We will also estimate the cost and cost-effectiveness of SAIA relative to treatment as usual using an activity-based costing approach (Aim 3). To our knowledge, this will be the first RCT of an organizational-level intervention to optimize the SSP-based PrEP delivery cascade. If successful, SAIA could be disseminated to the ≥430 SSPs nationally and in global settings, carrying the potential for exceptional impact amidst persistent HIV transmission in PWID.