The Long-Term Effects of a Co-Response Program on Patrol Call Volume for Mental Health Crisis-Related Calls: An Interrupted Time-Series Analysis

Background and Purpose

Mental health crises (MHC) impose substantial operational burdens on law enforcement agencies (LEA), which often serve as first responders. Traditional LEA responses to MHC also face criticism due to officers' limited training, potential for escalation, and adverse outcomes, underscoring the need for effective alternatives. Co-response programs, which pair trained officers with mental health clinicians, have emerged as promising strategies to divert MHC-related calls from traditional police-only responses. This study evaluates the effectiveness of a co-response program (CIRT) by examining its impact on the trends of MHC-related calls assigned to patrol units before and after the program’s introduction. The study’s research questions were: (1) Did implementing CIRT affect the trend of MHC-related calls assigned to day patrol units? (2) Did implementing CIRT affect call trends differently between the day shift (access to CIRT) and the night shift (no access)?

Methods

Interrupted time series analyses (ITSA) were used to examine administrative call data, focusing on eight MHC-related call types: Follow-Up (FU), Intoxicated Person (IP), Loitering, MHC, Self-Initiated Follow-Up (SIFU), Suicide Threat (ST), Trespassing, and Welfare Concern (WC). Single-group ITSA were employed to assess changes in monthly call volumes for day shift after CIRT was implemented in May 2022. Multi-group ITSA compared call trends between day and night shifts. Data spanned from February 2017 through September 2024, yielding 62 monthly pre-intervention and 28 monthly post-intervention data points for most call types. FU calls were introduced in July 2020 resulting in 22 pre-intervention and 28 post-intervention data points.

Results

The single-group ITSA indicated significant reductions post-CIRT introduction in IP, MHC, ST, Trespassing, and WC calls, alongside a notable immediate increase in SIFU calls. Multi-group ITSA found differences in call trends between shifts for IP, ST, and WC, with trends decreasing significantly more during day shift. There was also a significantly larger immediate increase in SIFU calls during day shift.

Conclusions and Implications

Results indicate that CIRT helped reduce MHC-related call volume for patrol units across several critical call types, particularly for high-risk scenarios such as ST, IP, and WC calls. Additionally, the increase in SIFU calls suggests more opportunities for proactive efforts by officers, possibly leading to more effective case work. The differences observed across shifts also suggest that expanding CIRT’s operational hours could enhance its overall impact.

Despite these positive outcomes, the lack of significant changes or significant differences between shifts for other call types, such as FU, Loitering, MHC, and Trespassing, highlight potential programmatic limitations. These might stem from the complexity or unique characteristics of these call types, which may require broader systemic interventions beyond the current scope of CIRT. As such, greater integration with community-based mental health and other supportive services could help maximize CIRT’s potential effectiveness and contribute to its sustainability.

Future research should further explore the long-term impacts of co-response programs on service recipients and police operations, the role of broader social determinants influencing MHC (e.g., housing, substance use, service access), and incorporate comparative studies across diverse jurisdictions to better understand and optimize co-response programs.