Responding to the increase in substance use, HIV, HCV, and overdose in New England (RISE-NE): Protocol for a prospective cohort study.

Background: High levels of opioid use, early introduction of drug supply contaminants, and increasing polysubstance use have led to intersecting epidemics of HIV, HCV, and overdose among people who use drugs (PWUD) in New England. Prevention services (e.g., syringe service programs, HIV testing) have been available in parts of New England for decades, yet significant service delivery gaps exist outside of major metropolitan areas. Further, racially minoritized PWUD face heightened discrimination in service settings and may be reluctant to access services. Our five-year, prospective cohort study, "Responding to the Increase in Substance Use, HIV, HCV, and Overdose in New England" (RISE-NE), will systematically examine rapidly evolving HIV and substance use trends in New England with the ultimate goal of informing the equitable scale-up of evidence-based HIV prevention and treatment services for PWUD.

Methods: We will recruit 1,200 PWUD across Massachusetts, Rhode Island, and Vermont to participate in our cohort. Beginning at enrollment, participants will complete semiannual surveys asking about their substance use patterns, ability to access healthcare and social support services, and HIV, HCV, and overdose outcomes. Biospecimen collection (e.g., HIV/HCV testing, oral fluid collection, and toxicology testing) will also occur semiannually. All aspects of the project will be guided by community leadership and a multilevel framework for HIV, HCV, and substance use outcomes.

Discussion: Using data from the RISE-NE cohort, we aim to: 1) examine regional transitions in substance use patterns and trajectories; 2) evaluate multilevel determinants of equitable access to and quality of services along the HIV, HCV, and overdose care continua; 3) evaluate the population-level causal effects of potential policy changes and interventions on our primary outcomes; and 4) rapidly address current and emerging research priorities. We discuss the anticipated strengths of this study as well as opportunities for training and dissemination.