Keeping crisis from becoming an emergency: Predictors of ED diversion in police-led behavioral health responses.

As law enforcement increasingly responds to behavioral health crises, both jail and Emergency Department (ED) diversion are essential considerations, as ED utilization for these cases often leads to extended boarding times and repeat visits, straining healthcare resources. Despite growing implementation of police-led jail diversion programs, a significant gap remains in understanding the specific factors that influence ED diversion outcomes, particularly for behavioral health crisis incidents. To identify predictors of ED diversion, we analyzed 10,904 behavioral health crisis incident records from the Massachusetts Department of Mental Health's Jail Diversion Program database (May-December 2023) using logistic regression and hybrid machine learning techniques. Co-response clinicians achieved the highest diversion rates, followed by CIT-trained officers, while evening/overnight incidents and police referrals were less likely to result in diversion. Community-based assessments showed modest improvements in diversion likelihood. Demographic predictor variables significantly influenced outcomes, while severe psychiatric concerns and substance use decreased diversion probability. These findings highlight the contribution of jail diversion programs, particularly through co-response clinicians, and suggest the need for expanded community mental health resources, particularly during off-hours. Results underscore how psychiatric acuity, substance use, and response team composition influence diversion outcomes, with implications for enhancing mental health nursing practice in crisis response systems.