Comparison of Unhoused and Domiciled Patients Evaluated for Trauma in a Level II Trauma Center

California has one of the highest rates of homelessness in the United States. Unhoused individuals often have complex medical and behavioral health disorders, frequently complicated by substance use disorders. They have a significant risk of sustaining traumatic injuries. This report compares unhoused and domiciled patients treated at our Northern California trauma center.

In this retrospective analysis of trauma patients we used data extracted from our institution's Trauma Quality Improvement Program Trauma Registry for January 1, 2019-April 22, 2022 and compared characteristics of unhoused and domiciled individuals. All unhoused patients in the registry were included in the analysis, as well as an equal number of domiciled patients who were randomly selected during the same time frame. We described and compared demographic and clinical characteristics.

Of 8,529 patients in the registry, 181 (2.1%) were unhoused, and we selected 181 domiciled patients to compare. Unhoused patients were more likely male (83% vs. 61%, P < .001) and younger (48.8 ± 12.3 vs. 55. 8 ± 23.7 years, P <.001). Both cohorts had similar Injury Severity Scores. However, unhoused patients had a higher rate of hospital admissions (76.8% vs. 61.9%, P <.001) and longer hospital stays than domiciled patients (4.0 [IQR 2.0-9.0] days vs. 3.0 [IQR 1.0-6.0] days, respectively; P = .02). A higher proportion of unhoused patients received alcohol-(85.6% vs. 74.6%, P = .01) and drug screening (56.4% vs. 30.4%, P < .001) than domiciled patients. Of those screened for urine drugs, unhoused patients had a higher positive rate (76.5% vs. 50.9%, P < .001). Unhoused patients were more frequently injured by assault (30.4% vs. 8.8%, P < .001) or pedestrian strike (21.5% vs. 3.3%, P < .001), whereas more domiciled patients were injured in falls (46.4% vs. 21.5%, P < .001) and motor vehicle accidents (29.8% vs. 8.3%, P < .001). Falls were most common in the oldest quartile for both groups. In both cohorts, a "sharp object" was the most common mechanism of assault injury (40.0% vs. 37.5%, respectively). Assault by firearm occurred in 14.5% of unhoused and 18.8% of domiciled patients. Overall mortality was 2.2%, with no significant difference between groups (1.7 vs. 2.8%, P = .70).

Unhoused patients were predominantly younger males with a higher incidence of substance use disorder and greater likelihood of injuries from assault and pedestrian strikes. Falls and assault with a sharp object were common in both cohorts. Unhoused patients were admitted more often and stayed longer in the hospital. Understanding the complexities of these patients can guide local and regional prevention and treatment measures.