Randomized trial of onsite versus referral primary medical care for veterans in addictions treatment.

Background: Patients presenting for treatment of substance use disorders (SUDs) often exhibit medical comorbidities that affect functional health status and healthcare costs. Providing primary care within addictions clinics (onsite care) may improve medical and SUD treatment outcomes in this population.

Objective: The objective of this study was to compare outcomes among Veterans' Administration (VA) patients who receive medical care within the SUD clinic and those referred to a general medicine clinic at the same facility.

Methods: Veterans entering SUD treatment with a chronic medical condition and no current primary care were randomized to receive primary medical care: 1) onsite in the VA SUD clinic (n = 358), or 2) in the VA general internal medicine clinic (n = 362). Subjects were assessed at baseline and at 3, 6, and 12 months postrandomization. Intention-to-treat analyses used random-effects regression.

Measures: Measures included SF-36 Physical and Mental Component Summaries (PCS, MCS), VA service utilization, SUD treatment retention, Addiction Severity Index (ASI) scores, 30-day abstinence, and total VA healthcare costs.

Results: Over the study year, patients assigned to onsite care were more likely to attend primary care (adjusted odds ratio [OR] = 2.20; 95% confidence interval [CI] = 1.53-3.15) and to remain engaged in SUD treatment at 3 months (adjusted OR = 1.36; 1.00-1.84). Overall, outcomes on the MCS (but not the PCS) and the ASI improved significantly over time but did not differ by treatment condition. Total VA healthcare costs did not differ reliably across conditions.

Conclusions: Compared with referral care, providing primary care within a VA addiction clinic increased primary care access and initial SUD treatment retention but showed no effect on overall health status or costs.