Illicit Drug Use Correlates with Negative Urine Drug Test Results for Prescribed Hydrocodone, Oxycodone, and Morphine

Background: A number of studies indicate that 10.8% - 34% of patients with chronic painuse illicit drugs. One hypothesis for this occurrence is that some patients may be supplementingtheir prescription medications with illicit drugs.Objective: The primary purpose of this retrospective data analysis was to test the hypothesisthat people whose urine specimens are positive for the medications that have been listed asbeing prescribed to them are positive for fewer illicit substances than those whose specimenswere negative for their prescribed medications. The secondary purpose of the study was tocorrelate the use of illicit drugs and the amount of prescribed medications excreted in urine.Study Design: A retrospective study of the incidence of patients using illicit drugs versus theirconsistency with reported medications.Methods: Using urine specimens from a cohort of nearly 400,000 patients whose identitieshad been redacted, and who were being treated for chronic pain with opioid therapy, thisstudy was performed to correlate the patients’ positivity with their prescribed medication to theprevalence of illicit substance use. A secondary study was conducted to correlate the amountof prescribed medication excreted in urine (measured in ng/mL) with the incidence of illicitdrug use. The specific prescription medications analyzed were hydrocodone, morphine, andoxycodone.Results: Specimens defined as negative for prescribed hydrocodone (27.3%), morphine(11.5%) or oxycodone (19%) were more likely to contain illicit drugs than those found tobe positive for the prescribed medication. The illicit drug prevalence among the inconsistentspecimens was 15.3% for hydrocodone, 23.8% for morphine, and 24.4% for oxycodone. Thesecondary study showed no statistically significant difference in the excretion level of prescribedmedication between those patients using and not using illicit drugs.Limitations: The study is limited in that no data was obtained to determine the causalrelationships of illicit drug use.Conclusions: This work supports the hypothesis that people who are positive for theirprescribed medications use fewer illicit drugs than those who do not take their medications.It may be beneficial for physicians to test more thoroughly for illicit drugs when patients’ drugtests are negative for their prescribed medications.Key words: Patients with pain, illicit drug use, hydrocodone, morphine, oxycodone.: