Evaluation of optimal urine screening and confirmation cut-off values for opiates, at a national reference laboratory

Çiğdem Karakükcü,Mehmet Zahid Çıracı,Muhittin Abdulkadir Serdar,Derya Kocer,Mine Yüce Faydalı

doi:10.1515/tjb-2020-0614

Abstract

Abstract Objectives To obtain optimal immunoassay screening and LC-MS/MS confirmation cut-offs for opiate group tests to reduce false positive (FP) and false negative (FN) rates. Methods A total of 126 urine samples, −50 opiate screening negative, 76 positive according to the threshold of 300 ng/mL by CEDIA method – were confirmed by a full-validated in-house LC-MS/MS method. Sensitivity, specificity, FP, and FN rates were determined at cut-off concentrations of both 300 and 2,000 ng/mL for morphine and codeine, and 10 ng/mL for heroin metabolite 6-mono-acetyl-morphine (6-MAM). Results All CEDIA opiate negative urine samples were negative for morphine, codeine and 6-MAM. Although sensitivity was 100% for each cut-off; specificity was 54.9% at CEDIA cut-off 300 ng/mL vs. LC-MS/MS cut-off 300 ng/mL and, 75% at CEDIA cut-off 2,000 ng/mL vs. LC-MS/MS cut-off 2,000 ng/mL. False positive rate was highest (45.1%) at CEDIA cut-off 300 ng/mL. At CEDIA cut-off 2,000 ng/mL vs. LC-MS/MS cut-off 300 ng/mL, specificity increased to 82.4% and FP rate decreased to 17.6%. All 6-MAM positive samples had CEDIA concentration ≥2,000 ng/mL. Conclusions 2,000 ng/mL for screening and 300 ng/mL for confirmation cut-offs are the most efficient thresholds for the lowest rate of FP opiate results.

Highlights

Opiates are one of the five classes of abused drugs mandated for testing in Drug Testing Program of many European countries, the USA, and Turkey
To obtain optimal immunoassay screening and LC-MS/MS confirmation cut-offs for opiate group tests to reduce false positive (FP) and false negative (FN) rates
At cloned enzyme donor immunoassay (CEDIA) cut-off 2,000 ng/mL vs. LC-MS/MS cut-off 300 ng/mL, specificity increased to 82.4% and FP rate decreased to 17.6%

Summary

Introduction

Opiates are one of the five classes of abused drugs mandated for testing in Drug Testing Program of many European countries, the USA, and Turkey. To detect medical or nonmedical drug abuse and/or illicit drug use health care providers usually order urine drug testing. Opiate drug testing can be ordered for identifying heroin use, opioid group prescription drug monitoring to evaluate possible overdoses, to evaluate adherence to prescription medications, or for workplace testing [1,2,3]. The cloned enzyme donor immunoassay (CEDIA) method used for opiate detection, with the application of the appropriate calibrator gives a positive result when morphine or codeine is present at greater concentrations than the defined threshold. Studies performed by the manufacturer reported that more than 20 additional drugs and their metabolites that share structural similarities with the target compound cross-react with the antibodies used in immunoassays and can cause positive results when present at the tested concentrations [5, 6].

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