Comparative Evaluation of the Accuracy of
Immunoassay with Liquid Chromatography
Tandem Mass Spectrometry (LC/MS/MS) of Urine
Drug Testing (UDT) Opioids and Illicit Drugs in
Chronic Pain Patients

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

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Comparative Evaluation of the Accuracy of Benzodiazepine Testing in Chronic Pain Patients Utilizing Immunoassay with Liquid Chromatography Tandem Mass Spectrometry (LC/ MS/MS) of Urine Drug Testing

January 2018 - Pain Physician ◽

10.36076/ppj.2011/14/259 ◽

2011 ◽

Vol 3;14 (3;5) ◽

pp. 259-270

Author(s):

Laxmaiah Manchikanti

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Tandem Mass Spectrometry ◽

Drug Testing ◽

Tandem Mass ◽

Index Test ◽

Chromatography Tandem Mass Spectrometry ◽

Urine Drug Testing ◽

Urine Drug ◽

Liquid Chromatography Tandem Mass

Background: Eradicating or appreciably limiting controlled prescription drug abuse, such as opioids and benzodiazepines, continues to be a challenge for clinicians, while providing needed, proper treatment. Detection of misuse and abuse is facilitated with urine drug testing (UDT). However, there are those who dispute UDT’s diagnostic accuracy when done in the office (immunoassay) and claim that laboratory confirmation using liquid chromatography tandem mass spectrometry (LC/MS/MS) is required in each and every examination. Study Design: A diagnostic accuracy study of UDT. Study Setting: The study was conducted in a tertiary referral center and interventional pain management practice in the United States. Objective: Comparing UDT results of in-office immunoassay testing (the index test) with LC/MS/ MS (the reference test). Methods: A total of 1,000 consecutive patients were recruited to be participants. Along with demographic information, a urine sample was obtained from them. A nurse conducted the immunoassay testing at the interventional pain management practice location; a laboratory conducted the LC/MS/ MS. All index test results were compared with the reference test results. The index test’s efficiency (agreement) was calculated as were calculations for sensitivity, specificity, false-positive, and false-negative rates. Results: Approximately 36% of the specimens required confirmation. The index test’s efficiency for prescribed benzodiazepines was 78.4%. Reference testing improved accuracy to 83.2%, a 19.6% increase, and 8.9% of participants were found to be taking non-prescribed benzodiazepines. The index test’s false-positive rate for benzodiazepines use was 10.5% in patients receiving benzodiazepines. Limitations: This study was limited by its single-site location, its use of a single type of point of care (POC) kit, and reference testing being conducted by a single laboratory, as well as technical sponsorship. Conclusion: Clinicians should feel comfortable conducting in-office UDT immunoassay testing. The present study shows that it is reliable, expedient, and fiscally sound for all involved. In-office immunoassay testing compares favorably with laboratory testing for benzodiazepines, offering both high specificity and agreement. However, clinicians should be vigilant and wary when interpreting results, weighing all factors involved in their decision. Key words: Controlled substances, benzodiazepines, opioids, illicit drugs, abuse, liquid chromatography tandem mass spectrometry, immunoassay, urine drug testing

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