title: The cost of treating substance abuse patients with and without comorbid psychiatric disorders.
abstract: OBJECTIVE
  Data from a national sample of patients with a primary diagnosis of a substance use disorder were analyzed to examine whether having a comorbid psychiatric diagnosis-a dual diagnosis-was associated with increased costs of health services over a six-year period and whether dually diagnosed patients used particular types of services more frequently.
  
  
  METHODS
  A national sample of substance abuse patients being treated in Veterans Affairs (VA) facilities were classified into two groups-those with a dual diagnosis (N=3, 069) and those with a single diagnosis of a substance use disorder (N=9,538). The sample was identified from two sources during a two-week period in 1990: outpatients in specialty substance abuse clinics and inpatients discharged with a substance-related diagnosis. Administrative data were used to track VA health care utilization and costs between 1991 and 1996.
  
  
  RESULTS
  Dual diagnosis was associated with a significantly increased total cost of care over the six years, which was primarily explained by increased utilization of outpatient psychiatric and substance abuse services. Costs for both groups decreased over time, but they decreased faster among dually diagnosed patients.
  
  
  CONCLUSIONS
  Having a comorbid psychiatric diagnosis appears to consistently increase the cost and utilization of services among patients with a primary diagnosis of a substance use disorder. These results are consistent with previous findings for dually diagnosed patients with a primary psychiatric diagnosis. The increased cost may simply reflect the greater severity of illness among dually diagnosed patients, but it may also indicate fragmented and inefficient service delivery.
authors.affiliation: Veterans Affairs Connecticut-Massachusetts Mental Illness Research, Education, and Clinical Care Center in West Haven and Yale University School of Medicine in New Haven, West Haven 06516, USA. hoff@biomed.med.yale.edu
authors.forename: R A
authors.initials: RA
authors.lastname: Hoff
authors.forename: R A
authors.initials: RA
authors.lastname: Rosenheck
mesh_terms: D001714:Bipolar Disorder / Q000150:complications* / Q000523:psychology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D017831:Diagnosis, Dual (Psychiatry); D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008297:Male; D008605:Mental Health Services / Q000191:economics* / Q000592:standards / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012559:Schizophrenia / Q000150:complications*; D012565:Schizophrenic Psychology; D012720:Severity of Illness Index; D019966:Substance-Related Disorders / Q000150:complications / Q000191:economics / Q000628:therapy; D014481:United States; D014493:United States Department of Veterans Affairs