Defining Study Populations in HIV Prevention Implementation Science Studies: A Case Comparison of 3 Ending the HIV Epidemic Projects.

Introduction: Implementation studies include both recipient populations, who will benefit from the study's evidence-based intervention, and study populations, who will participate in the intervention and contribute data to implementation outcomes. Decision making around inclusion criteria for the study population and whether to include the recipient population have significant implications for study design. We present 3 case studies of HIV prevention implementation studies that feature diverse study populations and describe the decision-making process around defining study populations to share generalizable lessons for the field.

Methods: We identified recipient and study populations for each study, described decision making regarding inclusion and exclusion criteria, and identified implications for measuring study aims.

Results: HIV prevention interventions focus on pre-exposure prophylaxis uptake and HIV testing in settings such as emergency departments, obstetrics/gynecology clinical practices, and free HIV testing sites. These studies were designed to inform scale-up of intervention strategies based on effectiveness, affordability, and feasibility. Decisions about whom to include in the study populations were based on context, strategies, and implementation outcomes.

Discussion: We identified important considerations across projects, including study context, strategies, and approaches. These factors can inform decisions around defining study populations to ensure successful measurement of study aims and sustainability of implementation outcomes.