Onsite versus Referral Models of Primary Care for Substance Abusing Patients
Andrew J. Saxon MD
VA Puget Sound Health Care System
Seattle, WA
Funding Period: October 1999 - March 2004

BACKGROUND/RATIONALE:
Veterans presenting for treatment of substance use disorders (SUDs) often have multiple and serious comorbid medical conditions that affect functional health status and health care costs. Prior studies show higher rates of medical follow-up when onsite primary health care was provided to patients with SUDs within an addictions clinic (onsite care). However, no data are available on differences between onsite versus referral models of primary care delivery in terms of clinical outcomes and total health care costs.

OBJECTIVE(S):
The objectives of this study are to compare patients with SUDs who receive onsite primary care in a VA outpatient addictions clinic to those referred for primary care to the general internal medicine clinic on: 1) medical outcomes and quality of life; 2) SUD treatment outcomes; and 3) overall health care costs. This information will assist in identifying practice guidelines for providing preventive services and treatment for acute and chronic medical conditions to individuals in SUD treatment.

METHODS:
This study is a randomized clinical trial with two treatment conditions: 1) onsite primary care in the Addictions Treatment Center (ATC; experimental); or 2) referral primary care in the General Internal Medicine Clinic (GIMC; control). Subjects are assessed at baseline and at 3, 6, and 12-month time points. The sample includes 720 veterans, newly presenting or returning to SUD treatment, who exhibited a chronic medical condition at screening, did not have a primary care provider; and did not present with a serious medical condition requiring ongoing care in three or more organ systems. Medical status outcome measures include scores on the SF-36, and total emergency room visits and medical or surgical inpatient admissions. Substance abuse outcomes are measured by treatment retention, changes in Addiction Severity Index (ASI) scores, and self-reported alcohol use. Lastly, overall VA health care costs per subject per the 12-month period following randomization are compared across groups. The main analysis involves intent-to-treat analysis of group (onsite vs. referral) by time (3, 6, 12-month) using random effects regression models.

FINDINGS/RESULTS:
A total of 2731 patients were screened and 720 (onsite: n = 358, referral: n = 362) subjects, aged 21-72, enrolled in this study. Final results indicate that the odds of attending a primary care appointment was significantly greater for on-site care group than the referral group after controlling for age (OR = 2.17; 95% CI = 1.51, 3.11; p < 0.001). In addition, the odds of subjects randomized to on-site care remaining engaged in addictions treatment are slightly higher at 60 (OR = 1.58; 95% CI = 1.07, 2.33; p = .021) and 90 days (OR = 1.36; 95% CI = 1.00, 1.84; p = .048) after controlling for age. We were not able to detect differences between groups in medical status over time as measured by the SF-36 and the ASI medical composite score, nor did we find differences in substance dependence status as measured by the ASI alcohol and drug composite scores and self-reported alcohol use. We anticipate that health care costs will be lower for the onsite care group; however, cost data has not yet been analyzed.

IMPACT:
No overall differences were detected between the onsite and referral subjects on physical and mental health status over the study course, suggesting that subjects did as well receiving primary care from an addiction clinic as from a general internal medicine clinic, the current standard of VA care. Thus preliminary results indicate that integrating primary care into a VA addiction clinic has the potential of increasing rates of primary care access with no apparent negative effect on overall health status relative to referral care.

PUBLICATIONS:

Journal Articles

1. Saxon AJ, Malte CA, Sloan KL, Baer JS, Calsyn DA, Nichol P, Chapko MK, Kivlahan DR. Randomized trial of onsite versus referral primary medical care for veterans in addictions treatment. Medical Care. 2006; 44(4): 334-42.
2. Zarkin GA, Bray JW, Mitra D, Cisler RA, Kivlahan DR. Cost methodology of COMBINE. Journal of Studies On Alcohol. Supplement. 2005; (15): 50-5; discussion 33.
3. Calsyn DA, Saxon AJ, Bush KR, Howell DN, Baer JS, Sloan KL, Malte CA, Kivlahan DR. The Addiction Severity Index medical and psychiatric composite scores measure similar domains as the SF-36 in substance-dependent veterans: concurrent and discriminant validity. Drug and Alcohol Dependence. 2004; 76(2): 165-71.
4. Saxon A, Sloan K, Nichol P, Howell D, Bush K, Calsyn D, Baer J, Felker B, Kivlahan D. Substance Dependent Individuals Often Lack Awareness of Their Medical Conditions. Drug and Alcohol Dependence. 2002; 66: S156-S156.
5. Davis TM, Carpenter KM, Malte CA, Carney M, Chambers S, Saxon AJ. Women in addictions treatment: comparing VA and community samples. Journal of Substance Abuse Treatment. 2002; 23(1): 41-8.
6. Saxon A, Calsyn D, Sloan K, Baer J, Kivlahan D, Felker B, Nichol P, Paden G, DeMarco F. Primary care attendance of substance dependent patients. Drug and Alcohol Dependence. 2001; 63: S1.

DRA: Health Services and Systems, Substance Abuse, Addictive Disorders
DRE: Quality of Care, Resource Use and Cost, Treatment
Keywords: Comorbidity, Organizational issues, Primary care
MeSH Terms: none