Comparison of Two Commercially Available Fentanyl Screening Immunoassays for Clinical Use

Area of Science:

• Clinical Chemistry
• Forensic Toxicology
• Analytical Chemistry

Background:

• Fentanyl is a potent synthetic opioid linked to widespread illicit drug use and overdose fatalities.
• Two FDA-cleared immunoassays, SEFRIA Immunalysis (IAL) and ARK, are available for fentanyl detection in urine.
• Limited comparative data exists for these two widely used fentanyl detection assays.

Purpose of the Study:

• To directly compare the performance of the IAL and ARK fentanyl immunoassays.
• Evaluate assay precision, cross-reactivity, and concordance with LC-MS/MS.
• Determine the clinical utility of each assay in fentanyl detection.

Main Methods:

• Fentanyl immunoassays (IAL and ARK) were performed on a Roche Cobas e602 analyzer.
• Assay precision was assessed using fentanyl dilutions above, below, and at the 1.0 ng/mL cutoff.
• Cross-reactivity testing included norfentanyl and fentanyl analogs; concordance was evaluated against LC-MS/MS in 90 patient samples.

Main Results:

• ARK assay demonstrated significantly lower imprecision (2.9%-6.4%) compared to IAL (18.9%-40.7%).
• Both assays cross-reacted with acetylfentanyl, acrylfentanyl, and furanylfentanyl; only ARK cross-reacted with norfentanyl.
• ARK assay showed higher concordance with LC-MS/MS (94%) than IAL (90%), improving to 96% when norfentanyl was included in LC-MS/MS confirmation.

Conclusions:

• The ARK fentanyl assay exhibits superior precision and greater concordance with LC-MS/MS compared to the IAL assay.
• ARK's ability to detect norfentanyl enhances its accuracy in identifying fentanyl exposure.
• These findings support ARK as a more reliable immunoassay for fentanyl detection in clinical and forensic settings.