Evaluating the impacts of critical time intervention implementation on health service utilization among...

Critical Time Intervention (CTI) is an evidence-based, time-limited case management practice that improves housing outcomes among homeless-experienced adults. While CTI's effect on housing outcomes has been well-studied, its impacts on health services utilization are less clear. In the context of a U.S Department of Veterans Affairs (VA) CTI implementation effort, we assessed relationships between CTI implementation, including fidelity, and Veterans' VA health services utilization.

We conducted a retrospective observational study of 9,051 Veterans who received services, 10/1/2019 to 5/1/2025, from one of 156 case management sites that worked with VA; 32 of these sites implemented CTI. Within the 18 implementing CTI sites that completed fidelity ratings, we compared health services utilization for Veterans (n = 2,022) at sites with adequate (n = 12 sites) vs. inadequate (n = 6 sites) fidelity. We performed multivariate regression using generalized estimating equations with clustering by site, adjusting for Veterans' demographics and diagnoses, and VA facility complexity. Regression models identified the impacts of CTI (versus non-CTI), and fidelity (adequate versus inadequate), on health service utilization; we used negative binomial regression for count outcomes (number of primary care, emergency department [ED], behavioral health, homeless services, outpatient medical-surgical visits) and logistic regression for binary outcomes (presence of inpatient mental health, or medical-surgical hospitalizations).

CTI Veterans had lower rates of utilization across all service types compared to non-CTI, including primary care (IRR = 0.98, 95% CI: 0.97-0.98), ED (IRR = 0.93, 95% CI: 0.90-0.95), homeless services (IRR = 0.91, 95%CI: 0.89-0.93) and hospitalizations (AOR = 0.79, 95%CI: 0.68-0.91). Among CTI Veterans, Veterans at sites with adequate fidelity had more primary care use (IRR = 1.04, 95% CI: 1.02-1.07), less ED use (IRR = 0.84, 95% CI: 0.80-0.90) and more homeless service use (IRR = 1.10, 95% CI: 1.05-1.15).

CTI Veterans had lower service utilization rates compared to non-CTI Veterans. However, adequate CTI fidelity is associated with increased primary care use and decreased ED use; this finding may be due to high-quality CTI implementation and/or site-level characteristics that enabled better CTI fidelity. Ensuring fidelity to CTI implementation may hold value in promoting optimal care linkages for homeless-experienced Veterans and other clients with high needs.