Comparison of the Microgenics CEDIA(R) Heroin Metabolite (6-AM) and the Roche Abuscreen(R) ONLINE Opiate Immunoassays for the Detection of Heroin Use in Forensic Urine Samples

Abstract

Current Department of Defense (DoD) and Department of Health and Human Services (HHS) procedures for the detection of heroin abuse by testing urine utilize an initial opiate (codeine/morphine) immunoassay (IA) screen followed by gas chromatography-mass spectrometry (GC-MS) confirmation of 6-acetylmorphine (6-AM), if the morphine concentration is above established cutoff. An alternative to the current opiates screen for heroin abuse is the direct IA for the metabolite of heroin, 6-acetylmorphine. In this regard, the performance of the Microgenics CEDIA heroin metabolite (6-AM) screening reagent was assessed. This evaluation was conducted on the P module of a Hitachi Modular automated IA analyzer calibrated using 6-AM at 10 ng/mL. Reproducibility, linearity, accuracy, sensitivity, and interferences associated with use of the 6-AM IA reagent were evaluated. The IA reagent precision (percent coefficient of variation (%CV)) around each of seven standards was less than 0.63%, with a linearity (r(2)) value of 0.9951. A total of 37,713 active duty service members' urine samples were analyzed simultaneously using the CEDIA heroin metabolite (6-AM) reagent and the Roche Abuscreen ONLINE opiate reagent to evaluate both the prevalence rate of 6-AM in the demographic group and the sensitivity and specificity of the reagents for the detection of heroin use. Of the 37,713 samples tested using the CEDIA heroin metabolite (6-AM) reagent, three samples screened positive at the DoD and HHS cutoff of 10 ng/mL. One of the three samples confirmed positive for 6-AM by GC-MS above the cutoff of 10 ng/mL, the two remaining samples confirmed negative for 6-AM at a GC-MS limit of detection (LOD) of 2.1 ng/mL. In contrast, the Roche Abuscreen ONLINE opiate IA produced 74 opiate-positive results for codeine/morphine, with 6 of the 74 specimens confirming positive for morphine above the DoD cutoff concentration of 4000 ng/mL (8% DoD morphine confirmation rate), only one of the 74 opiate-positive screen specimens confirmed positive for 6-AM above the 10 ng/mL GC-MS cutoff concentration. As a further check of the sensitivity and specificity of the Microgenics 6-AM IA reagent, human urine samples (n = 87) known to contain 6-AM by GC-MS, were re-analyzed using both IA reagents. All 87 of the samples screened positive using the CEDIA heroin metabolite (6-AM) assay. However, using the Roche ONLINE opiate reagent, 12 of the known 6-AM positives screened negative at the DoD and HHS screening cutoff of 2000 ng/mL (morphine). Of the remaining 75 samples that screened positive by the ONLINE opiate reagent, five of the samples did not contain morphine above the DoD GC-MS cutoff concentration of 4000 ng/mL and would not have required 6-AM analysis. However, under the HHS GC-MS morphine cutoff concentration of 2000 ng/mL all 75 samples would have required 6-AM analysis. Furthermore, using the current DoD opiate screen, 17 out of 87 samples known to contain 6-AM would have gone undetected (19.5% false-negative rate); additionally, even under the more stringent HHS opiate screening standards 12 out of the 87 samples known to contain 6-AM would also have gone undetected (13.8% false-negative rate). The Microgenics CEDIA heroin metabolite (6-AM) reagent assay appears well adapted for the rapid and specific detection of heroin abuse as an alternative for, or an adjunct test to, the current opiates (codeine/morphine) IA screening procedure.