Association of area-level income with patient reported long-term disability outcomes post-traumatic brain injury

Traumatic Brain Injury (TBI) affects 64-74 million people annually, often causing long-term disability. The influence of social determinants of health (SDOH), particularly neighborhood and built environments, on functional outcomes post-TBI remains underexplored. This study examines the association between census tract-level median household income- a proxy for area income- and self-reported functional outcomes in TBI-patients seen in a Southern California TBI clinic.

A retrospective cohort study of Neurology TBI & Concussion Clinic data (9/2022-1/2025) included patients ≥18 years with a known TBI mechanism and neurological symptoms who completed SDOH and functional assessments. SDOH factors included sex, race, ethnicity, insurance status, and median area income, determined by ZIP code using 2023 US census data. Disability was defined as Glasgow Outcome Scale-Extended-score ≤6 at index clinic-visit. Multivariable logistic regression was performed.

Among 148 patients (median age 46.5 years; 41% female, 75% mild TBI), the disabled cohort had higher proportions of poor insurance status (38% vs. 8%, p < 0.001), greater injury severity score (ISS) (9.0 vs. 1.0, p = 0.002), and lower median household income ($104,981 vs. $114,747, p = 0.020). Regression analysis showed poor insurance status (OR 5.80, CI 2.01-21.24, p = 0.003) and ISS (OR 1.06, CI 1.01-1.12, p = 0.027) predicted disability, but area income did not (OR 0.93, CI 0.79-1.10, p = 0.387).

Lower area income was associated with disability in unadjusted analysis but was not an independent predictor after adjusting for insurance and ISS. Findings highlight the need to explore individual and community factors influencing long-term TBI outcomes for targeted screening.