BackgroundThis study investigates the prisoner and prison-level factors associated with healthcare utilization (HCU) and the dynamic effects of previous HCU and health events. We analyze administrative data collected on annual adult prisoner-stay HCU (n = 10,136) including physical and mental chronic disease diagnoses, acute health events, penal circumstances and prison-level factors between 2013 and 2017 in 4 prisons of Canton of Vaud, Switzerland. Utilization of four types of health services: primary, nursing, mental and emergency care; are assessed using multivariate and multi-level negative binomial regressions with fixed/random effects and dynamic models conditional on prior HCU and lagged health events.ResultsIn a prison setting with health screening on detention, removal of financial barriers to care and a nurse-led gatekeeping system, we find that health status, socio-demographic characteristics, penal history, and the prison environment are associated with HCU overtime. After controlling for chronic and past acute illnesses, female prisoners have higher HCU, younger adults more emergencies, and prisoners from Africa, Eastern Europe, and the Americas lower HCU. New prisoners, pretrial detainees or repeat offenders utilize more all types of care. Overcrowding increases primary care but reduces utilization of mental and emergency services. Higher expenditure on medical staff resources is associated with more primary care visits and less emergency visits. The dynamics of HCU across types of care shows persistence over time related to emergency use, previous somatic acute illnesses, and acting out events. There is also evidence of substitution between psychiatric and primary care.ConclusionsThe prison healthcare system provides an opportunity to diagnose and treat unmet health needs for a marginalized population. Access to psychiatric and chronic disease management during incarceration and prevention of emergency or acute events can reduce future demand for care. Prioritization of high-risk patients and continuity of care inside and outside of prisons may reduce public health pressures in the criminal system. The prison environment and prisoners’ penal circumstances impacts healthcare utilization, suggesting better coordination between the criminal justice and prison health systems is required.