Evaluation of a Newly Formulated Enzyme Immunoassay for the Detection of Hydrocodone and Hydromorphone in Pain Management Compliance Testing

A new Hydrocodone Enzyme Immunoassay (HEIA; Lin-Zhi International, Inc.) was evaluated for the detection of hydrocodone and its main metabolite, hydromorphone. All specimens were tested with two different cutoff calibrators, 100 and 300 ng/mL, on an ARCHITECT Plus c4000 Clinical Chemistry Analyzer. Controls containing -25% (negative control) and +25% (positive control) of the cutoff calibrators and a drug-free control were analyzed with each batch. All 1,025 urine specimens were previously analyzed by ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS-MS) for opiates. Approximately, 33% (337/1,019) of the specimens yielded positive results by the HEIA assay at a cutoff concentration of 100 ng/mL and 19% (190/1,025) yielded positive results at the 300 ng/mL cutoff concentration. Of these presumptive positive specimens, UPLC-MS-MS confirmed the presence of hydrocodone and/or hydromorphone >100 ng/mL in 241 specimens and >300 ng/mL in 162 specimens, for each respective cutoff. With the 100 ng/mL cutoff, the HEIA demonstrated a sensitivity of 0.959, a specificity of 0.846 and an overall agreement with the UPLC-MS-MS of 87%. At 300 ng/mL cutoff, the HEIA demonstrated a sensitivity of 0.880, a specificity of 0.966 and an overall agreement of UPLC-MS-MS results of 95%. The Lin-Zhi HEIA 100 ng/mL cutoff assay demonstrated sensitivity for the detection of hydrocodone and hydromorphone in urine. The 300 ng/mL cutoff was less sensitive, but more selective, and should be part of an initial immunoassay screen, particularly in pain management compliance testing.