Affiliation:
1. Pain Management Center of Paducah, Paducah, KY, and University of Louisville, Louisville, KY
Abstract
Background: The challenge for physicians in treating chronic pain with opioids is to eliminate or
significantly curtail abuse of controlled prescription drugs while assuring proper treatment when
indicated. Urine drug testing (UDT) has been shown to be a useful approach in identifying patterns
of compliance, misuse, and abuse. However, significant controversy surrounds the diagnostic
accuracy of UDT performed in the office (immunoassay) and the requirement for laboratory
confirmation with liquid chromatography tandem mass spectrometry (LC/MS/MS).
Study Design: A diagnostic accuracy study of urine drug testing.
Study Setting: The study was performed in an interventional pain management practice, a
tertiary referral center, in the United States.
Objective: The objective of this study was to compare the results of UDT of immunoassay inoffice testing (index test) to LC/MS/MS (reference test).
Methods: One-thousand participants were recruited from an interventional pain management
program. Urine sample was collected from all the consecutive patients with demographic
information. Immunoassay testing was performed by a nurse at the location, laboratory assessment
was performed with LC/MS/MS.
Results of the index test were compared to the reference test in all patients. The sensitivity, specificity,
false-positive, and false-negative rates, and index test efficiency (agreement) were calculated.
Results: Overall, results showed that confirmation was required in 32.9% of the specimens. Agreement
for prescribed opioids was high with the index test (80.4%). The reference test of opioids improved the
accuracy by 8.9% from 80.4% to 89.3%. Non-prescribed opioids were used by 5.3% of patients. The
index test provided false-positive results for non-opioid use in 44% or 83 of 120 patients.
For illicit drugs, the false-positive rate by index test was 0% for cocaine, whereas it was 2% for
marijuana, 0.9% for amphetamines, and 1.2% for methamphetamines.
Limitations: The limitations include a single site study utilizing a single POC kit and a single
laboratory, as well as technical sponsorship.
Conclusion: The UDT with immunoassay in an office setting is appropriate, convenient, and
cost-effective. Compared with laboratory testing for opioids and illicit drugs, immunoassay inoffice testing had high specificity and agreement, demonstrating the value of immunoassay drug
testing. Because of variable sensitivity, clinicians would be well-advised to take a cautious approach
when interpreting the results.
Key words: Controlled substances, opioids, illicit drugs, abuse, liquid chromatography tandem
mass spectrometry, immunoassay, urine drug testing
Publisher
American Society of Interventional Pain Physicians
Subject
Anesthesiology and Pain Medicine