title: Diagnostic cost groups (DCGs) and concurrent utilization among patients with substance abuse disorders.
abstract: OBJECTIVE
  To assess the performance of Diagnostic Cost Groups (DCGs) in explaining variation in concurrent utilization for a defined subgroup, patients with substance abuse (SA) disorders, within the Department of Veterans Affairs (VA).
  
  
  METHODS
  A 60 percent random sample of veterans who used health care services during Fiscal Year (FY) 1997 was obtained from VA administrative databases. Patients with SA disorders (13.3 percent) were identified from primary and secondary ICD-9-CM diagnosis codes.
  
  
  METHODS
  Concurrent risk adjustment models were fitted and tested using the DCG/HCC model. Three outcome measures were defined: (1) "service days" (the sum of a patient's inpatient and outpatient visit days), (2) mental health/substance abuse (MH/SA) service days, and (3) ambulatory provider encounters. To improve model performance, we ran three DCG/HCC models with additional indicators for patients with SA disorders.
  
  
  METHODS
  To create a single file of veterans who used health care services in FY 1997, we merged records from all VA inpatient and outpatient files.
  
  
  RESULTS
  Adding indicators for patients with mild/moderate SA disorders did not appreciably improve the R-squares for any of the outcome measures. When indicators were added for patients with severe SA who were in the most costly category, the explanatory ability of the models was modestly improved for all three outcomes.
  
  
  CONCLUSIONS
  Modifying the DCG/HCC model with additional markers for SA modestly improved homogeneity and model prediction. Because considerable variation still remained after modeling, we conclude that health care systems should evaluate "off-the-shelf" risk adjustment systems before applying them to their own populations.
authors.affiliation: Center for Health Quality, Outcomes and Economic Research, Bedford VAMC/Edith Nourse Rogers Memorial Veterans Hospital, MA 01730, USA.
authors.forename: Amy K
authors.initials: AK
authors.lastname: Rosen
authors.forename: Susan A
authors.initials: SA
authors.lastname: Loveland
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Anderson
authors.forename: Cheryl S
authors.initials: CS
authors.lastname: Hankin
authors.forename: James N
authors.initials: JN
authors.lastname: Breckenridge
authors.forename: Dan R
authors.initials: DR
authors.lastname: Berlowitz
mesh_terms: D000328:Adult; D000368:Aged; D002204:Capitation Fee; D003211:Concurrent Review; D003953:Diagnosis-Related Groups / Q000145:classification / Q000191:economics*; D005260:Female; D005102:Health Expenditures / Q000706:statistics & numerical data; D006787:Hospitals, Veterans / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D020379:Risk Adjustment; D016320:Substance Abuse Treatment Centers / Q000191:economics / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000628:therapy*; D014481:United States; D014728:Veterans / Q000706:statistics & numerical data