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.