Medical costs of persons with drug use disorders among Medicaid managed care beneficiaries in Puerto Rico

Introduction: Drug use disorders (DUDs) substantially increase the costs of health care. Surprisingly not much is known about the specific types of medical services which give rise to the excess costs of DUDs. This study used 2007 claims data to examine the medical costs incurred by beneficiaries of the Medicaid Managed Care program in Puerto Rico with a drug addiction diagnosis. The study assessed the costs attributed to both physical and mental health services. Methodology: A total of 6,313 persons had at least one drug abuse related claim. A comparison group without a DUD claim was extracted from the pool of all beneficiaries. It was stratified by gender, age, and geographic region. A random sample was selected of approximately five times the size of the number of beneficiaries with a DUD in the equivalent stratum. Medical expenditures were calculated by multiplying probability, frequency, and cost of use. A logistic regression model was used for the probability of use, a Poisson regression model was estimated for the frequency of use, and a log-linear regression was estimated for the average cost. Results: Mean per-person annual medical costs increased for patients with a DUD in all categories except outpatient physical services. Beneficiaries with a DUD had, on average, $4,539 in annual costs while the comparison group had only $2,601. Conclusions: About half of the excess costs incurred by persons with DUDs fell on physical health services. There are significant savings in treating this population, in both treatment costs and associated medical care expenditures.