Direct costs of opioid abuse in an insured population in the United States.
OBJECTIVE
To (a) describe the demographics of opioid abusers; (b) compare the prevalence rates of selected comorbidities and the medical and drug utilization patterns of opioid abusers with patients from a control group, for the period from 1998 to 2002; and (c) calculate the mean annual per-patient total health care costs (e.g., inpatient, outpatient, emergency room, drug, other) from the perspective of a private payer.


METHODS
An administrative database of medical and pharmacy claims from 1998 to 2002 of 16 self-insured employer health plans with approximately 2 million lives was used to identify "opioid abusers"--patients with claims associated with ICD-9-CM (International Classification of Diseases, 9th Revision, Clinical Modification) codes for opioid abuse (304.0, 304.7, 305.5, and 965.0 [excluding 965.01]). A control group of nonabusers was selected using a matched sample (by age, gender, employment status, and census region) in a 3:1 ratio. Per-patient annual health care costs (mean total medical and drug costs) were measured in 2003 U.S. dollars. Multivariate regression techniques were also used to control for comorbidities and to compare costs with a benchmark of depressed patients.


RESULTS
740 patients were identified as opioid abusers, a prevalence of 8 in 10,000 persons aged 12 to 64 years continuously enrolled in health care plans for whom 12 months of data were available for calculating costs. Opioid abusers, compared with nonabusers, had significantly higher prevalence rates for a number of specific comorbidities, including nonopioid poisoning, hepatitis (A, B, or C), psychiatric illnesses, and pancreatitis, which were approximately 78, 36, 9, and 21 (P<0.01) times higher, respectively, compared with nonabusers. Opioid abusers also had higher levels of medical and prescription drug utilization. Almost 60% of opioid abusers had prescription drug claims for opioids compared with approximately 20% for nonabusers. Prevalence rates for hospital inpatient visits for opioid abusers were more than 12 times higher compared with nonabusers (P<0.01). Mean annual direct health care costs for opioid abusers were more than 8 times higher than for nonabusers ($15,884 versus $1,830, respectively, P < 0.01). Hospital inpatient and physician-outpatient costs accounted for 46% ($7,239) and 31% ($5,000) of opioid abusers. health care costs, compared with 17% ($310) and 50% ($906), respectively, for nonabusers. Mean drug costs for opioid abusers were more than 5 times higher than costs for nonabusers ($2,034 vs. $386, respectively, P<0.01), driven by higher drug utilization (including opioids) for opioid abusers. Even when controlling for comorbidities using a multivariate regression model of a matched control of depressed patients, the average health care costs of opioid abusers were 1.8 times higher than the average health care costs of depressed patients.


CONCLUSION
The high costs of opioid abuse were driven primarily by high prevalence rates of costly comorbidites and high utilization rates of medical services and prescription drugs.