(205) Predictors of illicit substance use assessed by urine drug monitoring in patients prescribed opioid medications

Abstract

Oral opioid therapy is widely used in pain management. This study evaluated the relationship between patient characteristics and the use of illicit substances assessed by urine drug monitoring in patients prescribed opioid medications. Urine samples from patients prescribed ≥1 opioid medication were analyzed using liquid chromatography/tandem mass spectrometry. Samples were tested for the presence of illicit substances (including cocaine metabolite [benzoylecgonine], heroin metabolite [6-MAM], marijuana metabolite [THC], MDMA, and phencyclidine). Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were calculated using multiple logistic regression analysis with the following independent variables: sex, age decade, geographic region, and primary payer. Between January 2013 and June 2015, a total of 450,018 samples were tested, of which 46,592 (10.4%) were positive for ≥1 illicit substance(s). Marijuana (38,158 [12.2%] samples) and cocaine (8574 [2.0%] samples) were the most commonly detected illicit substances, whereas heroin was detected in only 1649 samples and no other illicit substances were detected in >125 samples. The factors most strongly associated with likelihood of detecting an illicit substance were sex (men, 13.1% vs women, 8.2%; aOR, 1.76; 95% CI, 1.73-1.80), age (progressive decrease from 18.3% for 20-29 years of age to 0.4% for 80-99 years; aOR for 80-99 years compared with 20-29 years was 0.02; 95% CI, 0.01-0.03), and primary payer (highest rate for Medicaid [16.4%] and lowest rate for Medicare [8.1%] compared with self-pay [12.5%]; aOR for Medicaid was 1.34; 95% CI, 1.29-1.38; aOR for Medicare was 0.63; 95% CI, 0.61-0.65). Among patients prescribed opioid medications, use of illicit substances was common and varied with patient characteristics. Understanding factors associated with the likelihood of positive urine testing for illicit substances may better inform strategies for using urine drug testing in the clinical management of patients on prescribed opiate therapy. Support: Ameritox Ltd.