Do mechanisms that link addiction treatment patients to primary care influence subsequent utilization of emergency and hospital care?

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 nomnethadone 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 nomnethadone 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.