Impacts of Residential Segregation and Comorbidity on Racial Disparities in Acute Care Utilization

Purpose: To examine whether living in highly segregated communities or having comorbidity is associated with an increased risk of acute use of emergency and inpatient services (i.e., acute care utilization [ACU]) among racial minorities. Methodology: This longitudinal study included adult patients who underwent health-related social needs screening during their medical appointments within the Mass General Brigham healthcare system from March 2018 to January 2023. Our primary outcome was 180-day ACU defined as a composite outcome of all-cause emergency departments visits or hospital admissions following the most recent screening. Residential segregation was assessed using the index of dissimilarity, with a score of 0.6 or higher indicating extremely high segregation. Results: Among the 81,571 patients, 38% were non-White, and 28% were Hispanic. Approximately 18% lived in highly segregated communities and 55% had comorbidity. Accounting for demographic and clinical characteristics, Cox regression model found that living in highly segregated areas was generally not associated with the risk of 180-day ACU. Compared to White, non-White had a higher risk of ACU (HR = 1.07 [95%CI: 1.02 – 1.12]). Patients with comorbidity had a higher risk of ACU relative to their counterparts without comorbidity (HR = 1.65 [95%CI: 1.58 – 1.73]). Among patients in highly segregated areas, non-White experienced a 26% higher risk of ACU, compared with White in the same areas. However, for patients with comorbidity, non-White showed only a 5% higher risk of ACU relative to White. Conclusions: We found an additive effect of residential segregation on racial disparities in ACU. Comorbidity is a risk factor of ACU for all patients.