Long-term patterns of service use and cost among patients with both psychiatric and substance abuse disorders

OBJECTIVES. This is a longitudinal study designed to determine: (1) if patients dually diagnosed with psychiatric and substance abuse disorders incur higher health care costs than other psychiatric patients and (2) if higher costs can be attributed to particular subgroups of the dually diagnosed or types of care. METHODS. Two cohorts of veterans treated in Veterans Affairs mental health programs at the start of fiscal year 1991 were followed for 6 years: one cohort of inpatients (n = 9,813) and the other of outpatients (n = 58,001). Data were analyzed on utilization of all types of Veterans Affairs health care. Repeated measures analysis of variance was used to examine cost differentials between dually diagnosed patients and other patients. RESULTS. Dually diagnosed outpatients incurred consistently higher health care costs than other psychiatric outpatients, attributable to higher rates of inpatient psychiatric and substance abuse care; however, this difference decreased with time, Costs were substantially higher in the inpatient cohort overall, but there were no differences in cost between dually diagnosed and other patients. CONCLUSIONS. In an atmosphere of cost cutting and moves toward outpatient care, the dually diagnosed may lose access to needed mental health services. Possibilities of developing more intensive outpatient services for these patients should be explored.