Association of outpatient alcohol and drug treatment with health care utilization and cost: revisiting the offset hypothesis.
OBJECTIVE
This study examines the hypothesis that treatment reduces medical utilization and costs of patients with substance use problems.


METHODS
Adult patients (N = 1.011; 67% men) entering the outpatient chemical dependency recovery program at Sacramento Kaiser Permanente over a 2-year period were recruited into the study. Medical utilization and costs were examined for 18 months prior and 18 months after intake. To account for overall changes in utilization and cost, an age, gender and length-of-enrollment matched nonpatient control group (N = 4,925) was selected from health-plan members living in the same service area. Multivariate analyses controlling for age and gender were conducted using generalized estimating equation methods, allowing for correlation between repeated measures and nonnormal distributions of the outcome variable.


RESULTS
The treatment cohort was less likely to be hospitalized (odds ratio [OR] = 0.59; p < .01) and there was a trend for having spent fewer days (rate ratio [RR] = 0.77; p < .10) in the hospital in the posttreatment period compared to pretreatment period. These patients were also less likely to visit the emergency room (ER) (OR = 0.64; p < .01) and had fewer ER visits (RR = 0.81; p < .01) following treatment. Inpatient, ER and total medical costs declined by 35%, 39% and 26%, respectively (p < .01). Reductions in cost were greater for the treatment cohort when compared with the matched sample (p < .05). Among women, there were significant reductions (p < .05) in inpatient, ER and total costs for the study cohort when compared with the matched sample; among men, the reductions in inpatient and ER cost (but not total cost) were significantly larger (p < .05) for the study cohort when compared with the matched sample. For the treatment cohort, the change in medical cost was not significantly different by gender. Changes in cost were significantly different across the various age groups (p < .05) for the study cohort and the matched sample. Among those in the group aged 40-49 years, the decline in cost for study cohort was significantly larger (p < .05) than for the matched sample.


CONCLUSIONS
For patients with substance use disorders entering treatment, there was a substantial decline in inappropriate utilization and cost (hospital and ER) in the posttreatment period. The disaggregated pattern of posttreatment decline in utilization and cost is suggestive of long-term reductions that warrant a longer follow-up.
Parthasarathy
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Division of Research, Kaiser Permanente Medical Program, Northern California, Oakland 94611, USA.
Weisner
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Hu
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Moore
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D000293:Adolescent; D000328:Adult; D000437:Alcoholism / Q000191:economics / Q000534:rehabilitation; D000553:Ambulatory Care / Q000191:economics; D002140:California; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D017048:Health Care Costs; D006300:Health Services Misuse; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008329:Managed Care Programs / Q000706:statistics & numerical data; D008605:Mental Health Services / Q000191:economics* / Q000706:statistics & numerical data*; D008875:Middle Aged; D016320:Substance Abuse Treatment Centers / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000191:economics* / Q000534:rehabilitation*; D014600:Utilization Review / Q000706:statistics & numerical data