title: Do mechanisms that link addiction treatment patients to primary care influence subsequent utilization of emergency and hospital care?
abstract: BACKGROUND
  Patients with drug use disorders are heavy users of emergency department (ED) and inpatient hospital care. This study examines whether formal mechanisms to link addiction treatment patients to primary medical care, either directly on site or by off-site referral-when compared with an absence of said mechanisms-might reduce these patients' use of ED and hospital services after substance abuse treatment.
  
  
  METHODS
  We used longitudinal data from 6 methadone maintenance programs with 232 patients, 24 outpatient nonmethadone programs with 1202 patients, and 14 long-term residential programs with 679 patients in the National Treatment Improvement Evaluation Study. Multivariate logistic models controlling for health status and medical service utilization before treatment examined whether provision of medical services on- or off-site during treatment linkage led to reduced use of ED and hospital services in the year after treatment compared with no such provision.
  
  
  RESULTS
  On-site delivery of primary care reduced subsequent ED and hospital use among patients in methadone maintenance and long-term residential compared with the nonlinkage condition but not in outpatient nonmethadone programs. Off-site referral for medical care reduced subsequent ED visits but not hospitalizations in long-term residential programs.
  
  
  CONCLUSIONS
  These findings suggest that for some treatment modalities, stronger primary care linkage mechanisms decrease subsequent utilization of expensive ED and hospital services. Future study should examine the cost implications of these strong linkage mechanisms and ways to strengthen linkages to off-site medical care.
authors.affiliation: Program to Integrate Psychosocial and Health Services, Research Service, Providence Veterans Affairs Medical Center, and Department of Medicine, Brown University School of Medicine, Providence, Rhode Island 02903, USA. pfriedmann@lifespan.org
authors.forename: Peter D
authors.initials: PD
authors.lastname: Friedmann
authors.forename: James C
authors.initials: JC
authors.lastname: Hendrickson
authors.forename: Dean R
authors.initials: DR
authors.lastname: Gerstein
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Zhang
authors.forename: Michael D
authors.initials: MD
authors.lastname: Stein
mesh_terms: D000328:Adult; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006760:Hospitalization; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008485:Medical Audit; D008691:Methadone / Q000627:therapeutic use; D015999:Multivariate Analysis; D011320:Primary Health Care / Q000458:organization & administration*; D012017:Referral and Consultation; D016320:Substance Abuse Treatment Centers; D019966:Substance-Related Disorders / Q000534:rehabilitation*; D014481:United States
chemical_list: D008691:Methadone