Mental illness, traumatic brain injury, and Medicaid expenditures

Objective: To estimate the rates of mental illness among Medicaid beneficiaries with traumatic brain injury (TBI) and associated Medicaid-paid expenditures. Design: Retrospective claims-based calendar year data. Setting: Claims data. Participants: Medicaid recipients with diagnosed TBI and mental illness who received Medicaid services in 4 states in 1995. Interventions: Not applicable. Main Outcome Measures: Annual expenditures for total, inpatient, and noninpatient services, as derived from Medicaid personal summary files. Mental illness and TBI were identified by using International Classification of Diseases, 9th Revision, Clinical Modification codes recorded in Medicaid claims. Results: Of a total of 493,663 Medicaid recipients, 3641 (0.7%) were diagnosed with TBI in the 4 states. Significant demographic and racial differences were found in the rates of TBI; 18% of patients with TBI were diagnosed with serious mental illness. People with TBI in the age group 40 to 49 years were more likely to have a mental disorder. There were significant differences in estimated total, inpatient, and noninpatient expenditures between those with and without mental illness. In general, those with serious mental illness had higher Medicaid-paid expenditures than those without any mental illness. Conclusions: Psychiatric comorbidity in TBI increases the overall expenditures in this population. This increased cost is an important consideration in programming for those with TBI.