PROJECT SUMMARY/ABSTRACT Over the past 25 years, the United States (US) has witnessed a fourfold increase in its prison and jail population, with nearly 70-90% coming from minority and lower socioeconomic backgrounds. To illustrate, one out of every three Black males and one out of every six Hispanic males born in 2001 are projected to experience incarceration during their lifetimes, in stark contrast to just one out of seventeen White males. There is a glaring lack of data on their surgical care, and what is known is deeply troubling. This study, titled 'Unlocking Equity: Validating Methodologies and Evaluating Surgical Care for Incarcerated Individuals,' seeks to deepen our understanding of the healthcare of incarcerated individuals and ultimately impact the existing disparities in mortality and timely surgical care. Inmates possess the unique constitutional right to healthcare, yet the extent, quality, and outcomes after surgery are unknown. The reasons for this knowledge gap are complex, none the least of which is the difficulty of identifying these patients in healthcare databases. Identifying incarcerated individuals in healthcare databases relies on the International Classification of Diseases 10th edition codes, Z65.1 ("imprisonment and other incarceration") and Y92.14x ("prison as the place of occurrence of the external cause") or the Agency for Healthcare Research and Quality admission source code. These codes are used ubiquitously in healthcare databases, but their validity is unestablished. To address these critical gaps in the surgical care of incarcerated individuals, our study has two aims. In Aim 1, we will validate methods for identifying incarcerated patients in electronic medical records (EMR) and claims databases. The accuracy of these codes is crucial for gaining insights into healthcare delivery for incarcerated individuals requiring surgery and in-hospital medical care. In Aim 2, we will evaluate the timeliness of surgical care and outcomes (morbidity, mortality) of incarcerated patients in New York State undergoing inpatient surgery using validated codes. This study examines the public health of incarcerated individuals, a group that predominantly comes from underserved and disadvantaged communities. It introduces an innovative method for identifying incarcerated patients in healthcare databases, serving as an invaluable model for future research. Our multidisciplinary investigator team and Expert Advisory Panel have expertise in the healthcare of incarcerated individuals, health outcomes, surgical care, disparities, and policy evaluations which ensures the validity of the study. In essence, this research addresses pressing issues in incarcerated healthcare and provides a methodological framework to inform future studies, facilitating informed policy decisions and improved healthcare practices for an underserved community.