Utilization and Costs of Mobile Medical Units for Veterans Experiencing Homelessness.

Importance: The Veterans Affairs (VA) health care system Homeless Patient Aligned Care Teams (HPACT) program began staggered deployment of mobile medical units (MMUs) to 24 VA medical centers in late 2023 to increase outreach and health care access in community settings for veterans experiencing homelessness. Objectives: To examine the early association between MMU implementation and the use of outpatient and inpatient services and costs among veterans experiencing homelessness. Design, Setting, and Participants: This longitudinal cohort study was performed at 24 HPACT sites from October 1, 2021, to March 30, 2025. Participants included veterans experiencing homelessness who used MMU care. Changes in utilization and costs in each fiscal quarter before and after site MMU implementation were estimated for patients treated by MMU relative to those receiving usual care. Exposure: MMUs providing primary care and other services in community settings. Main Outcomes and Measures: VA outpatient visits by type of care, VA inpatient stays by type of care, and VA outpatient, inpatient, and total costs of care, analyzed using linear difference-in-differences and event study models. Sensitivity analyses included a propensity score-matched comparison group and comparisons of all veterans experiencing homelessness in MMU sites and other HPACT sites. Results: A total of 2700 patients who used MMU care were included in the analysis (mean [SD] age, 60.5 [12.6] years). Of these, 2523 patients (93%) were male and had a mean (SD) Elixhauser comorbidity score of 3.3 (2.8). Per fiscal quarter, patients using MMU care had increases in mean number of visits for primary care (0.43; 95% CI, 0.30-0.56), homeless programs (1.40; 95% CI, 1.05-1.76), mental health intensive case management (0.03; 95% CI, 0.01-0.06), and emergency department care (0.06; 95% CI, 0.03-0.10); decreased mean inpatient stays for substance use disorders (-0.002; 95% CI, -0.004 to -0.0004) and domiciliary care (-0.002; 95% CI, -0.004 to -0.001); and increased mean total costs ($1724; 95% CI, $1172-$2276) compared with those receiving usual care after MMU implementation. Conclusions and Relevance: In this cohort study of veterans experiencing homelessness, patients receiving MMU care had small increases in primary care, mental health intensive case management, emergency department, and housing and other homeless services and few decreases in inpatient care at higher health care costs. MMUs may not reduce all types of acute care, but they may be an effective modality to reach veterans experiencing homelessness with access barriers and greater complexity and needs for care.